My understanding is these are usually sponsored online or live players who are getting paid by the site to boost sign-ups or promote their own Twitch stream/brand. They're only playing because they're contractually obliged to participate in it as marketing for the site or their own personal brand.
To the OP this means it really doesn't matter if sponsored players are in freerolls, since the freerolls in question wouldn't exist without them in the first place.
Chris Moneymaker, who won millions of dollars in the 2003
world series of poker Main Event would play every Sunday afternoon with us "Land of the Free" Americans who are only allowed by our government to use the play chip side of
poker stars... well Chris was a "sponsored pro" by the site, but there he was each Sunday in the highest stakes play chip tournament of the week.
He clearly enjoyed playing with us, but as you might expect, once his contractual obligation to Poker Stars ended last year, well that was the last we saw of Money800 in our play chip tournament. LOL So it's pretty apparent, he wasn't there for the love of poker (well, kinda sorta he was), but he was just there because he was a good sport and agreed to show up and play each week. It really was a cool thing, altho the truth is, I didn't quite have the big
bankroll back then as I have today, and so I didn't get to play many times against Chris... but def a cool thing to get to compete against a
wsop Main Event Champion every Sunday and test our skills!!! Like everything in life... those were the good old days, never to return again... (kinda like Black Friday here in America, sigh).