Hi and welcome to guitar = )
As you by now probably realize after reading through several answers, the actual answer to "Do I have to learn chords" is both 'yes' and 'no'.
The short reasoning for 'yes' is because the instrument was designed to be able to easily accommodate chording. When we use tools (yes, a guitar is actually a tool) we usually use them to their full capability or choose a different tool. As mentioned there are several other musical 'tools' designed to play single notes at a time.
The short reasoning for 'no' is because we live in a free society where if you wish to use a Swiss army knife to peel a potato when you have a potato peeler sitting right there, you are free to make that choice. So the guitar can be used to play only single notes at a time if that's all you want it to do. But you don't, and let me explain.
Learning, remembering and playing chords is the hardest things most guitarist 'have to do' (arguably in today's world). We were ALL there with you at some point. We spent a lot of time. We were frustrated and unsure. We invented new unique cuss words. And then we crossed over an invisible finish line we never saw in front of us, which means one day we picked up our guitar and just made the chord our brain commanded our hand to do as we had practiced so many times. Just like one day after attempting to tie our shoes a hundred times, we just did that. It's how our brains learn.
Pay attention to this part, because it will guide you through any learning experience, not just guitar: You have two parts to your brain that mirror RAM and a hard drive in a computer. Your RAM is for very short term and blistering fast access. You load things in and are quickly able to use them. If too many things are loaded in, it locks up or gets too laggy to be usable. With little to no practice, loading up your short term memory with a new chord fingering overloads it. You can only do it very slowly, one finger at a time. Here's the important part - in order for your brain to 'allow' something to be transferred from short term memory to the 'hard drive', or (you guessed it) the long term memory, you have to repeat something many times. After x amount of repetitions, the brain makes a decision that this 'thing' you are doing is important enough to store in the hard drive, and it stores it in chunks. Now when you recall the activity, the brain loads in those chunks from the hard drive and things become much easier and fluid.
The whole point of that section was to explain that because you are finding something difficult, you are not getting the immediate pleasure reward. So you are questioning why bother. IF you understand the process as explained above, you might look back on all the thousands of tasks you have mastered, like using a keyboard to be able ask a question here, and realize that all you need is patience. Chording will come if you persist through enough repetitions. Everyone's number of repetitions necessary to get something stored into long term (subconscious) memory is different. You may need more repetitions, or you might get it quickly.
I would advise you to approach this, or any task in this way. First, this is a musical instrument - warm up! Look up online or videos on proper finger stretching and warm up exercises/runs. They will prepare your fingers to play without injury, and most are also designed to sneak in some invisible dexterity training too.
After warming up, practice immediately what you are trying to learn that's new. If it's chords, have a few that are used in songs you need them for, and practice forming them - SLOWLY. Look at them and load them into your RAM, and relay that to your fingers. Try the next one. Go back and do the first one again. Back and forth between them - slowly. Spend 10-15 mins doing this. Let me explain what you are doing! You are loading in your brain one chord, then discarding it to add the next one. Alternating causes your short term memory to dump the previous chord and load the new one. Repetitions! After a bit, your brain will be like "Whoa, this person is obsessed with these two things - perhaps I should pass these over to the hard drive for faster access" - and just like that, you don't need the chord on paper or on screen anymore. The trick to mastering any skill is to trick the brain into passing learned bits of the desired final skill to the subconscious.
After doing that for awhile, play the songs you know and that are FUN! Reward yourself. Get some dopamine to go.. you deserve it for practicing something difficult beforehand! Repeat this process the next time you can sneak in a guitar session!
Finally, there's this bit you posted - "...are there some songs where they are totally necessary and can't be substituted with finger picking?"
See, if you are substituting single notes, you are actually already playing a form of chording known as 'arpeggiation' (or playing arpeggios). An arpeggio is a chord played as single notes.
And with that, the answer to your original question becomes a solid 'yes' - you must indeed play chords in music. The trick to that is that there are several ways to play (or 'voice') chords on a guitar specifically, but all songs use chords, and all melodies are built using chords. Chords are not something your hand does, chords are musical arithmetic. They exist mathematically (known as music theory). What your hand does on the guitar is known as voicing. Even if you only play one or two notes, there is an implied corresponding chord, so literally everything you do musically is attached to a chord and a chord progression.
Learn the voicings used in the songs you are learning and take it slow. The rest will be rewarded to you over time. Good luck and hang in there.. we all had to pass through this phase. It's doable! = )