I think I know the answer to that one. Maybe. Here goes:
It's the very first pitfall encountered, time is boring.
TIME IS NOT BORING G DAMMIT. (when played properly)
I'll go out on a limb here and say that all the drummers who "screw up" a straightforward song with too much crap...They don't how "not" to embellish, even when embellishing detracts (which they are most definitely not aware of)
Keeping just the beat is boring to most drummers. I suffered from that for way too long. It's the biggest pitfall I've seen, thinking that just keeping the time/beat...is boring. It's so not. It's completely opposite in fact. Actually it works MUCH better than impressing everyone with stupid out of place fills. These are the drummers that likely can't groove either, because time is boring and fills are everything. Not.
To simplify...they just don't get it yet. I can very much relate. I didn't get it for the entire first phase of my drumming adventure. (16 years) Not their fault. It's just where they are on the journey. They are playing for themselves, not the song. They haven't musically matured to the point where they play like a team player in the support section. Drums are not the featured instrument.
feel
Ego ego ego....I have to be great....I have to impress everyone...I have to play a lot of notes, Keeping time is too boring...It's all abut the drums...I, I, I, Me Me Me! So backwards.
You can't hold a 6 YO kid responsible for paying the electric bill. It's the same thing. They just aren't musically mature yet. It's hard not to diss them, but they don't deserve it if they are clueless. Ignorance is definitely a valid excuse here.