If Lemmy were styled after an old-school forum board rather than reddit I'd agree with you, but because profile pics on Lemmy are so tiny they're basically pointless. However they're just large and colorful enough to be distracting. Lemmy's format can feel a bit cluttered as is, and I'd rather be able to scan and quickly identify important info--such as whether a comment poster is OP--than have my eye get caught by something superfluous and purely aesthetic like a profile pic. Thus I'd rather they do away with them entirely, at least in bylines.