I think some of the posts here miss a little bit of the context as to why things like this happen in the first place. It's only in the last handful of years that a stack for logging has really become mainstream. Chances are a lot of these types of logging solutions predate that and used whatever persistence technology was readily available. Writing to files on web servers can be a pain, and these logs will have to be queried at some point, so storing it in a database is not a bad idea, especially when better options have only recently become available.

The problem is that relational SQL is bad for logs, but by the time it gets to the scale where it's problematic that there's too much volume in the logs to make anything "easy". Simultaneously there's a lot of business value in that log data that you don't want to lose.

Yes, SQL's a poor fit for logs, but it's a better fit then a lot of other things, including not logging at all. Better solutions exist, but they don't exist in a bubble, and there's a cost to integrating them and migrating to them. A lot of these comments seem to be judging a technology decision based solely on hindsight without realizing that there are legitimate reasons for logging to SQL.