Well, it matters to the customer if their WordPress site goes down because it was infected by malware that sends out spam or makes clicks on Google Adwords.
This happened with someone I was working with, to try and rescue their WordPress.
Ironically, the site went down only because the malware that I'm guessing was scraping Google or making clicks on google adwords or something (I just skimmed the malicious code, it wasn't entirely clear to me what it did) -- had a bug in it that brought down their site. If it had been bug free, it could have kept using their site for it's malicious purposes for years without them ever noticing.
This happened with someone I was working with, to try and rescue their WordPress.
Ironically, the site went down only because the malware that I'm guessing was scraping Google or making clicks on google adwords or something (I just skimmed the malicious code, it wasn't entirely clear to me what it did) -- had a bug in it that brought down their site. If it had been bug free, it could have kept using their site for it's malicious purposes for years without them ever noticing.