Some do peer to peer for 1:1, then upgrade to actually using the SFU for more participants. But that's a challenge on its own, so when more than 1:1 is expected

Some do peer to peer for 1:1, then upgrade to actually using the SFU for more participants. But that's a challenge on its own, so when more than 1:1 is expected, you might just prefer to use SFU from the start, and save the hassle for when to switch between those two models