If Heroku works for you, that's fine, but for lots of people it doesn't. For example, Heroku only supports HTTP, not TCP. There are a number of technical limitations Heroku places on apps that other platforms like Flynn don't.
There are lots of reasons why users need a different, or especially an open source, PaaS.
Some users run into scaling problems when their products grow beyond a certain point. Others want to have more control over their infrastructure for compliance, governance, or other administrative reasons. Others have huge deployments and want to save money by using their own cloud accounts.
It varies from customer to customer, but for many Heroku isn't an option or isn't the best option.
Totally with you on this - all pretty valid points; but, I'd say Heroku does still work for a lot of people, especially if they can get past the cost (which, imho is worth it from a focus and time point of view).
There are lots of reasons why users need a different, or especially an open source, PaaS.
Some users run into scaling problems when their products grow beyond a certain point. Others want to have more control over their infrastructure for compliance, governance, or other administrative reasons. Others have huge deployments and want to save money by using their own cloud accounts.
It varies from customer to customer, but for many Heroku isn't an option or isn't the best option.