That actually varies in fiction. In some tales, sure, no problem. In others, the witches or warlocks are “marked” in some way.
Faustian bargains where the cost is paid longterm mat have negligible effects during a campaign.
RAW you can flat out ignore ALL fluff for any class. Depending on the campaign mood or theme, it would be a pity to not play into those “costs” in some immediate sense.
Caveat: I’m much more of a fan of magic systems that have SOME risk, from full on mutations and corruption (Dungeon Crawl Classics, WFRP, Dark Heresy) to thematic temptations for more power (Star Wars’ the Force). Even the X-Men had SOME kind of flaw or drawback about their powers.
It’s compelling fiction, that’s for sure.
Again: if your table couldn’t care less about these things, all the best.
But I don’t see the point in a Warlock without ANY special ties or consequences for their powers. Like a Paladin without any kind of code of honor or oath, or a Cleric without devotion to any Faith.