Oracle no longer publishing their test cases hardly constitutes "transforming MySQL into a 'free-open-sore, closed-outer-shell' RDBMS", moreover there is no evidence that folks are adopting PostgreSQL because they're afraid of MySQL vendor lock-in. If one feels they must pay from MySQL they can give their money to Oracle, Percona, or MariaDB, all of which whom will happily provide MySQL support for a fee.
PostgreSQL is quickly becoming the main go-to alternative for people who are obsessed with the hip-now shiny thing. These are some of the same folks who will mindlessly advocate zsh over bash, tmux over screen, htop over top, and ack over grep.
Many of my clients were using MySQL, got freaked out by what's going on with Oracle, and decided to at least look into PostgreSQL. They were very impressed with what they saw, and in some cases admitted that they should have gone with PostgreSQL from the beginning.
In my experience, everyone who tries PostgreSQL loves it and sticks with it. That doesn't make it a mindless choice, or the "hip-now shiny thing." It does mean that Oracle's decisions are encouraging people to look at alternatives, and that the alternative is, in fact, often better than what they're currently using.
You make a reasonable point in your first paragraph. There is no strong evidence of vendor lock-in in MySQL's case, though Oracle's past history makes for legitimate suspicion on the part of prospective MySQL users.
It's unfortunate that your second paragraph is either trollish or ill-informed. Sure, there is a part of group-think about Postgres' popularity in some communities, but Postgres has a number of advantages over MySQL (though I'd say MySQL has a better multi-server story). Implying this plays little part in its growing popularity is condescending.
Postgres has been quietly competent since before this generation of hipsters was born. It is nice to see the user base grow, since MySQL had a huge boost for a long time just for being more noob friendly in a way postgres unfortunately never tried.
PostgreSQL is quickly becoming the main go-to alternative for people who are obsessed with the hip-now shiny thing. These are some of the same folks who will mindlessly advocate zsh over bash, tmux over screen, htop over top, and ack over grep.