i agree with thestrahl. you have to have one of those hyper mouse wheel thingy's if you want to take the record or even get near it. and its also basically no skill required, like all you do is scroll. and with actual clicking its more stamina and cps you can get and anyone can do it. like as in your mouse doesn't really matter for cps ( at least in my case)

so yeah i personally agree with left clicks only because it requires more skill and makes speed running this more viable for other people getting in to it.

edit: forgot to add this, i say that the speedrunning should be split in to two different categorys for cookie clicker speedrunning because if you cant get a impressive run for left click it just gets berried under all the mouse wheel speed runs. and if you were trying to flex on a friend he would ask why you where so low on the leader board and to get good.

and this may not all make sense cause im bad at writing