No offense taken. The most popular PHP framework around currently is Laravel. It has a minimum requirement of 7.2 also. Symphony has 7.2.5. Cake is minimum 7.2. It's not just us.
Not everyone is in control of their server. Some people like to build products they can sell to people at which point having shared hosting requirements that are a challenge pose a blocker to people buying their products.
Composer is not a requirement for the "download and go" packages. We use it to keep a couple of third-party packages up to date. If you want to use Composer then it works out of the box. I have never come across a hosting configuration that cannot be setup to work with /public formats. CPanel is the challenging environment but even there it's possible.
December 2020 is a year away. We have time to evaluate and make the change.
As for type hints and Entities, in my experience things have a tendency to come out of the database as a string, which is what makes casting and mutations helpful.
The fun I have with this argument is that when I decided to make 7.2 the minimum a while back I got a fair amount of flack for that. No winning I guess.
