The post references a StackExchange question [1] which has a simple analysis, and four helpful suggestions (similar to yours), as to which the author states:
"I tried the first suggestion, but the results weren't promising. As experimenting with each suggestion could easily take at least half a day, I proceeded with a way I knew would work efficiently and reliably"
Correct. When I see developers using 'distinct' and complaining about some query performance, it's almost always the developer doing it incorrectly rather than an issue with the database.
