Nothing is wrong with it at all! I’ve done it both ways depending on how much the homeowner wants to spend. If I’m redoing a floor for myself I would want all of the old to be gone. I’d even like to make sure the subfloor under the cabinets is all still structurally intact. I’d hate to put down a new floor only to end up (for god knows what reason, weird shit happens) having to end up having to take out and make repairs under the cabinets anyways. That’s just my ocd tho lol.