Back in the days of Mysql w/ MyISAM engine it was sometimes way faster on big data-sets and underpowered DB servers to do the query exactly this way. Even with all the correct indices in place the JOINs (especially if more than one table was in game) would often just freeze the server for 15-20 minutes, while joining data at the app level in the for loop and with the lookup tables for id-s would typically take only a few seconds. Obviously this is an obsolete hack for long time now...
I can imagine that, but MySQL didn't really start to become a competitive relational database until the 3.23 timeframe (around 2000), and it is hard to imagine MyISAM (with no actual transaction support) being used for a production database except under very carefully controlled circumstances.
To some degree that was true of a lot of earlier competing databases as well, which tended to take escalating locks on everything from the page level on up just to implement basic read consistency. So any transaction of any type could easily lock up a random set of unrelated rows if not entire tables until completion.
