There are no social platforms that are VC backed that aren't going to at some point resort to the lowest common denominator of making a buck at someone's expense. And when you aren't paying for the product, then you are no longer able to control that exchange.
Google started off with Don't be Evil - now they force adverts from your competitors on your registered trademark and force you to advertise your own company name or lose customers - meanwhile for Google's products, no one can advertise in the same manner.
Facebook - well - that one is too long to even dive into.
Twitter - has done ok, sort of - but the problem with it's no policing policy is pretty rampant harassment that is also dealt with in an inconsistent manner.
That's why paying for something you create an exchange where the company providing that service has an incentive to keep you happy, not some advertising company. There is also competition that will naturally spring up, competing for that dollar.