I wouldn't mind changing it. One reason they're split is that PC might have an advantage through camera control. This may not lead to 'faster' times, but combined with holding 'w' to go straight will make some levels easier to achieve those times.
Another reason is they haven't released yet, so I personally wouldn't know if there's a difference. If you all prefer combining them that's fine too as long as they're basically identical.
personally i think having them divided (Switch, Xbox/PS4, PC/Mac) Is fine. When the game comes to Xbox / PC ill be running it and doing some IL times on both platforms so ill be filling the boards up. If they where to change then probably keep the full game and chapters divided but if everyone wants the IL's combined then that's fine. ATM because only the switch has the game it does look bear but once its released for other platforms it would be good to see who the world recorded holders are for each platform. Again im not overly bothered about the IL page but i think it's fine.
I think until we find a major difference between platforms there is really no point in keeping it seperated. It will just discourage poeple to play more than anything.
I mean isnt the point of speedrunning also finding the fastest platform / version to run on? 99% of games dont seperate, for exemple, Japenese version from EU or NA just because the text or controls are faster. At this point you could argue making seperate leaderboards for keyboard / controller players. But you guys do as you feel