Well you're using their PAAS for free. Ultimately a minority of paid users are paying for all the free users, it can't go on for ever.This is true for Heroku, as well as any PAAS that has a free tier right now.
If you use Heroku for hobby projects you don't need scaling and load balancing, you might need a DB on your instance so a dropplet at DO, or using EC2 makes more sense than paying 7$ for a immutable app on Heroku servers.
Clearly they don't believe that kind of marketing to be worth it now, but I'm sad to see that option go away.
Now, if you're abusing the service, that's a different story...
Assuming you have any of the billion spiders out there hit your site more often than once an hour, there's no such thing as sleeping.
My approach was always to start projects on Heroku, and then to keep them there when they graduated to needing more resources than the free tier provided.
Now all my projects start on a little DigitalOcean instance, and when they graduate to needing serious resources, they don't go to Heroku.
Now, howerver, I have to weigh any given project against my overall budget of hours. If I put up my weekend project, do I need to kill that project from a few months ago? Do I want to start paying for hosting for a site that will probably never go anywhere?
I suppose I'll just go back to hosting on DO/EC2/Etc. A single small instance of any major provider could handle the traffic for all my projects put together. It's slightly more work, although there are some cool projects like Dokku that make it less so. Heroku's main selling point for me was convenience and simplicy, and it's been progressively losing that over the last year or so.