When children go to grade school they learn two main subjects among many others: Math and Reading/Writing. These subjects have some crossover, but are obviously separate. As you become advanced students the ability to do both skills is merged in some advanced subjects.
I recommend students start with guitar by studying multiple subjects in every practice, where the subject categories are (roughly) are rhythm (chords, arpeggios, fingerpicking, and strumming) and lead (scales, reading tabs, arpeggios, and reading music). Merging these skills more and more as you become more skilled is an indication that you are becoming more advanced.
This is more or less what @Tim seems to be saying. He is right: Guitarists who know both lead and rhythm are better at both.
This is not to say that you should avoid anything. @Todd Wilcox is right. You should learn what you like. I also recommend in addition that you should spend some time working on basic skills that you might miss, to help you become well rounded. Don't avoid things because they are hard, or you don't like them. It takes a long time to learn guitar, and eventually you may want to be able to do some other style than the one you want to do now. All the work on your journey will improve all your skill to some degree, and at the same time you can be held back by any basic skills that you did not bother with.
I would argue that it does not take longer to learn both. It takes a long time to learn guitar, but working in parallel like this multiplies the value of your practice time.