Their release model changed with MySQL 8 -- they do rolling point releases every quarter with new features sprinkled in as they're ready. Quite a few new major features have been released that way, including INSTANT alters, parallel index builds, CLONE plugin, major changes to how UNDO logs are sized... it's more like Windows 10's release model.
Very recently they've mentioned they'll be changing this again to have separate LTS releases, which is a positive change stability-wise.
If you've got a bit of time to spare, here's a 30min walk through of physical design in the database. https://youtu.be/x0P4zAptTiA
In this talk, we start at 10,000 transactions per second, and just by altering the design we get to 20,000 transactions per second... all on a 5 year old laptop.
And at no time did we ditch any constraints (primary or foreign). The claim that you can't get performance with constraints on a database is a myth
I mean, was that 20,000 transactions that are likely to have lock contention related to foreign key constraints? Because otherwise you are measuring the wrong thing.
What kind of lock contention is that? (In Oracle) you'd have to be (a) manipulating the values of a primary key and (b) choosing not to index the child FK column.
Even without (b) I'd be asking "Why are you altering primary keys?" because it pretty much aint a primary key anymore if you're doing that :-)
Anyone who says no investment has been into MySQL I suspect never took the time to read the features/release notes for MySQL 8
https://dev.mysql.com/doc/refman/8.0/en/mysql-nutshell.html