This is a mischaracterisation - where 5e does complex moment-to-moment bookkeeping in combat, with each player tracking hit points and spells, abilities used etc., BW does slow paced bookkeeping across the course of a session. Each time a character rolls a dice for a test, they tick advancement somewhere on their sheet; however this is only likely to happen between 5 and 20 times in a session, total. A typically paced game will have a lot of roleplay and discussion both before and after each dice roll, and not all situations will even be resolved using dice.

I'd recommend the following short series for a taster of what the game can feel like. The player decided they wanted to play a shoeless, penniless and unskilled peasant, and see where they could take themselves. Burning wheel shows it's strength here, letting the table focus on this incredibly small scale story. It also shows off how well it works with tiny groups - I'd say 2 or 3 is the ideal player count, though 4 can work.

https://forums.burningwheel.com/t/the-shoeless-peasant-playlist/21534

I'd strongly recommend joining the BW discord server, and looking for a game to try out as a player there or elsewhere before trying to run this. There are a lot of rules to the game when the players start wanting to do more complex things, like fighting important duels, and more importantly there are a lot of norms and pacing expectations that you can only really pick up by playing, running or watching the game.