Why do we need in-game time? Currently you need to get all Bonus Objective to get a WR, imo the only thing you should do in speedruns is being fast.

In-game time makes sense for those who don't have a capture card. An in-built timer also means there are no splitting issues.

In-game time is generally preferred when possible since it doesn't have things like load times and lag which could affect time. The point of speedrunning is mastery of a game which, although I usually don't like the bonus objectives (looking at you No Traction Action), it does fall in the same vein as "to be at the top you need to be good"

We can use in-game time, that wasn't my problem! My problem was the Bonus Objectives because then you need to be a bit slower to get these but the goal is actually to be fast.

There are actually many games that use IGT over RTA and many of these games do things that are slower for real time but save time on the in game timer, this game isn't the only one. The game was designed with bonus objectives in mind and the community decision is to follow whatever it's said at the end of the game