Seems sort of irrelevant if one is already a touch typist.
Personally, I find labeled keycaps pleasant for a few reasons: One is that I have a glowy keyboard, which is aesthetically enjoyable to me (or I wouldn't have one), and it wouldn't be as much fun if the LEDs were just shining up through identical dots.
Also, I find it useful to re-register my fingers. I added Braille dots to all the alphabetic keys, so I can also do this by touch, but a quick glance down also does the trick. For whatever reason, checking that my pinky will hit p is the most common case here.
Last, I find it helpful with chords, especially when I add a new one to the firmware. Layers as well. I do intend to converge on what my other two layers do, but there's been some churn, and it's easier to remember what a key does on a particular layer when it has a distinct symbol. Modified key commands which I frequently use are part of the muscle memory, but when I'm adding a new command to the repertoire, precisely where the key finger needs to go once the modifying finger has hit command/control/meta isn't kinesthetically obvious at first.
Note that this is from a baseline of touch typing, so I naturally stop double-checking things once I've done them enough. If you don't touch type, do yourself a huge favor and learn. Some people find blank keycaps helpful here, especially if they have many years of whatever ad-hoc system they use to type with.
Some people aesthetically prefer no keycaps as well. Also functionally: it's just easier for them to think about a key geometrically rather than symbolically. I don't think there's a one-for-all answer on this.