No.
That's about all I'll add, lol.
It sounds like a really bad idea. Sometimes you've installed a version where everything works to your satisfaction, and not wanting to update, if things doesn't affect you in any significant way.
Also this way, if a bug sneaks in, it'll affect everyone using it, instead of just the few that updated to it.
Also, the data transfer will be an issue in this case. We've all seen how the website dies when everyone rushes in to get the new modpack when a new version of World of Tanks is out.
Right now, (I think) most of the data is handled by sites like MediaFire and such.
If it was all to be handled by the website... ugh... RIP website.
We'll see what Aslain has to say..