I've used both, and honestly, it depends on what you're building. For a simple server, a regular VPS is probably fine. But for a multiplayer game with leaderboards, player accounts, and matchmaking, a game backend service saves you a ton of headache. You get auth, data storage, and server discovery built in, no need to stitch together a bunch of different tools. I switched because setting up user accounts and save files myself was taking forever.