Huh, that's an interesting observation- is there good signal on older accounts not being sources of astroturf? Anecdotally/datally I've dug randomly into a few suspicious comments elsewhere and though the account is old really looks sketch, like an article submission every other day for years on end but almost no comments, other odd patterns.
"Great article that contains some pithy aphorisms that I expect to see again and again."
"Great article that is approachable enough to share with less technical folk. Thank you!"
"Good article, I would add the good things about working with media different than text. For example, describing images."
They are similar indeed. The users have been around for a while so unless their accounts have been taken over, I wouldn't worry.