Back in 2007 I built myself a gaming PC with two brand new GTX 8800 cards (SLI, baby!) and nearly cooked/choked them to death in first week of operation. What I learned back then was that nVidia drivers did not create a proper fan curve that would ramp up with rising temperatures and that I needed a piece of 3rd party software named Afterburner to keep my system cooled.
It's been nearly 20 years and probably a dozen different graphic card models since then. I have just finished installing a render box for my wife with a 3090 in it. Installed the drivers. Installed the Afterburner. Tuned it.
Then it dawned on me: Is this still a necessary step? What would happen if I did not install Afterburner? Don't nVidia drivers control the fans properly?
Logic dictates it would be crazy for the official drivers not to keep the card cool, but I've been doing it one way for so long that I am too afraid to experiment (risking hardware damage?).
When you're afraid to let evidence lead you, next best thing is surely asking strangers on the internet - so here it goes: Is MSI Afterburner necessary? What would happen if I don't install it? Do YOU have it installed?
Fan Control is great. Like you mentioned, the possibility to create mix fan curves is really helpful. For example, if either CPU or GPU gets hot, you can set all the case fans to ramp up. There are good guide videos on YouTube that shows how to set it up.