Ok, now we are getting somewhere. There is no guarantee that they will be a big part of the stock market. It is not "absolutely" sure, for them or for any new public stock. That's why the indices have/had the the rules they (used) to have, to wait and see if a newly IPOed stock actually becomes a big part of the market before it becomes part of the index.

Why did they change the rules for these companies? That's what people want an explanation for. That's what is fishy about all this. I'm not asking you to explain something that seems normal. I'm asking you to explain something that doesn't make sense