I think you underestimate the usefulness of a hosted environment. I need a really good reason to set up a full stack myself and incur the maintenance problems of system upgrades and hardening an entire OS.
That said, you are right that there are plenty of hosting providers with ruby/python available in some capacity.
In the comment that you're replying to, my exact words were "are there really that many people who have access to 'only' PHP, but not whatever framework they would like? (from django to rails)". After I said that loads of people are happy with Wordpress, and other similar services, including with plugins, and just use that instead of php and html.
So, whereas previously (in the 90s) you would have a big jump from HTML only with maybe PHP or you jump up to paying for a server every month and having to lock it down and administer it yourself, now, the former category has access to loads more 'hosted' service possibilities so that what you can do with "wordpress only" has substantially increased; meanwhile, the latter category has come down substantially, due to instances on the cloud being so much cheaper and the amount of uptake making it much more worth it for a company to put out a standardized image with a few frameworks, etc.
So my point was twofold. Firstly, the old 'hosted content' users have access (and use) substantially fuller services, and the old 'full stack' users AND some of the old 'php is all I can use' users now have EASY access to a full instance or whatever framework you want.
Between the two, I think your comment doesn't have much currency.
That said, you are right that there are plenty of hosting providers with ruby/python available in some capacity.