Paying customer here. I hope they don't do that. If you consider a dyno to be a unit of some set of resources, having a free dyno tells you exactly what to expect. Although most apps do not scale as a linear multiple of the number of dynos you have due to other bottlenecks, the resources you have increase linearly. So, having a single unit of resources to try out is a really great model that would give you some peace of mind in scaling.

After all, most successful apps will quickly outgrow their free dyno (and that is without even considering at least an additional dyno for background services).