And you lose commenters (like me) and give away control over parts of your site as well as content.
Also by the time you outsource a comment system due to CPU your site probably is big enough for a "real" CMS.. or atleast better hardware, it's not like a good vserver is expensive nowadays.
Not everyone is a knowledgeable web developer, or is interested in the security maintenance of a custom solution, of which you have even less knowledge about the data they collect.
For example, I have a friend who runs a small business selling music samples. He uses WordPress because it is a simple solution that can do a lot for him without a super amount of technical savvy.
I think WordPress is disgusting, but the point is, there is a market for these products. If you feel strongly against this trend, you should consider developing one that drives your vision that has similar practical value.
