The underlying principle at work here is: Notated music "doesn't show everything."
Compare, say, the sheet music of the Moonlight Sonata to a midi file capturing a performance of it.* The midi file records the exact velocity with which each key was pressed, how long it was held, and the exact timing from note to note. As the performer emphasizes certain notes expressively, or delays them, or quickens the pace slightly, all these details are recorded. Traditional staff notation doesn't document this level of detail—and that's kind of a good thing. For one thing, it would be tremendously confusing to read, and for another, it would leave no room for personal "interpretation." Every performance would be the same. So every human performance contains infinite data points of "interpretive" decisions to emphasize or de-emphasize certain notes, to modulate their attack or release in certain ways, or to manipulate the timing intentionally, and most composers are happy to leave this granularity of detail up to the performer.
The concept of metric emphasis is one of these. It's also complicated by the fact that it's an abstract concept. In an actual musical phrase, other factors might influence emphasis, perhaps even in ways that contradict the meter (minuets, mazurkas, ländlers, and even basic rock-and-roll can feature heavy emphases on what are supposed to be "weak" beats).
But the idea is: Yes, the first note, the downbeat, is almost always thought of as emphasized. In practice it will often get some emphasis as well, though of course you could imagine "overdoing it." (And "overdoing it" will look different in different contexts—oom-pah bands or disco are built on heavy metric emphasis, but other genres might lighten up.)
Now what about DAWs, or metronomes, or other robots? What about a human performance of a piece like Steve Reich's Clapping Music that aspires to make every note equal in emphasis?
At that point we run into the fact that meter is a concept. Yes, most of the time it will also affect the human-produced sound, but even when it doesn't, it may be superimposed on the actual sound. You can turn on a metronome and set it to 240. You may then think of that series of undifferentiated pulses as quarter notes (in 3/4, 4/4, or any other number of beats, imagining an emphasis on a downbeat. Or you can think of the metronome's sounds as representing eighth notes with a quarter-note speed of 120, or triplets at 40, etc. You can perform a piece with subtle, limited metric emphasis, but still make the meter much more important in your mind.
* Disclaimer, there's a lot I don't know about MIDI. Just making an analogy.