> 3. It's performance is predictable.  99% of issues 
  > with performance are easily solved with the right index

This is one of my least favorite things about MySQL. The "explain" feature is much less informative than that offered by MSSQL or Postgres, so figuring out what indexes or tuning to apply is harder than it needs to be.

And then when you do have everything indexed correctly, MySQL is significantly dumber (edit: looks like I'm significantly dumber! see correction below) about using those indexes than MSSQL or Postgres.

For example: those two can do index-only SELECTS. If table "foo" has columns A, B, C, D, E, and F and I've created an index on A and B, why can't "select A,B from foo" be served directly from the index? Postgres and MSSQL do it, and it's a huge performance boost in those two.

Postgres also lets you do some amazing things with partial indexes, indexes on computed values, etc.

MySQL might not be horrible here, but out of the 3 major relational databases I've used, it's clearly the weakest at this so it's funny to hear it touted as a strength.

Edit: Good news - I was wrong; MySQL does support index-only selects (covering indexes). User morgo also pointed out the improved JSON format for explain as well.