WordPress became popular at a time when LAMP hosting was easy, widespread, and affordable. It's one reason WordPress largely supplanted Movable Type, which was an early popular blogging platform / CMS / static site generator. Because Movable Type was Perl-based, it was more difficult to host.
Internally, Movable Type had a really nice object persistence / ORM abstraction, with support for MySQL, Postgres, SQLite, and Oracle. Meanwhile, iirc around this time WordPress internally had raw queries strewn about its codebase, which certainly would have been difficult to support multiple DBs. (I haven't looked at WP since then so I don't know if this is still the case.)
Faced with shrinking market share and being out-executed on features by WordPress/Automattic, Movable Type actually removed Postgres and SQLite support in response! Then again, these DBs weren't nearly as popular back then as they are today.
Internally, Movable Type had a really nice object persistence / ORM abstraction, with support for MySQL, Postgres, SQLite, and Oracle. Meanwhile, iirc around this time WordPress internally had raw queries strewn about its codebase, which certainly would have been difficult to support multiple DBs. (I haven't looked at WP since then so I don't know if this is still the case.)
Faced with shrinking market share and being out-executed on features by WordPress/Automattic, Movable Type actually removed Postgres and SQLite support in response! Then again, these DBs weren't nearly as popular back then as they are today.