I remember it differently - we needed replication for "hot" backups. At that time, scalability was a major issue - so anyone (including businesspeople) wanted to have a scalable architecture. MySQL spoke to the practical (default install on cPanel hosts, easy replication) and the aspirational (you're going to blow up and need to scale).

Digg.com also had a really influential technical team - hearing about how they did things set a lot of baseline defaults for a lot of people.

maybe you were on the more funded side of history in this. As for me, Digg is way after LAMP got solidly plonked into "what I need for a dynamic website on cheap".

Essentially, start at 2000-2001 and more and more people going into running websites for all kinds of reasons (forums, blogs, webshops, etc. often hosted on low end offerings)

I didn't enter the workforce until 2004, so yeah missed some of the early early days of PHP/MySQL. I used it for government work, was definitely not well funded haha! But I suspect digg started with MySQL b/c of similar reasons as anyone else, then helped amplify the cycle.

"Cheap" is the key word here, and that usually meant shared hosting, which was like 99% MySQL.