On paper, Postgres sounds great. But of all the people on here cooing about it, how many are actually using the tool?
I don't know who has the stronger hype machine on Hacker News: Postgres or Rust.
The reasons were both technical (better performance with this kind of workload, great reliability, excellent code quality, ...) and political (we have contributed numerous patches to PostgreSQL - not sure if you ever tried to do that with MySQL).
If you think there's a simple MySQL -> PostgreSQL migration tool (or a migration between arbitrary databases), you're foolish. Databases are not that interchangeable - all databases have some issues with specific workaround, and the 'good bits' are database-specific too. And those things are anchored in the application code, so if you think there's a simple migration tool, you'll be disappointed.
Postgresql's excellent documentation made the move much more practical than it would have been using a clearly less documented tool. (One such as MonetDB circa 2005: http://www.monetdb.org/ .)
Similarity to standard SQL and Oracle are also nice if one happens to work in an heavily regulated industry where one may have to migrate to certified platforms.
I've worked on projects that were using it a decade ago. To this day at a different job I'm still building on it. Shipping it our products to customers, building internal tools on it, and we've have purchased a handful of self-hosted applications that have happened to run on it.
You're generalizing from your own experience and assuming that's everyone's experience. Availability of dump and load tools to move from mysql don't really that much. MySQL isn't poison just because there is a new hotness. Keeping old shit on mysql, and using postgres for new things is a much more common migration strategy.
Of course, they are on two sides of the maturity spectrum. Postgres is used by lots of people and we're happy it works so well. Rust is not even released yet, but looks very promising.