Was security a huge problem in Wordpress ? I work in the tech industry too, but never came across security as an issue. Or is it about the plugins bringing in the unreliability ?
Plugins. The plugins are a never ending stream of XSS, SQLi, and other vulnerabilities. I used to intern on a web security team at Mozilla that hunted down these kinds of things and the entire experience revealed how easy it was to compromise your entire site because of a single plugin. During my six months there, I think I discovered 30+ plugins with issues. Most developers were responsive but some ignored us and the issues were never fixed.
I've personally never used Wordpress, but when I look at my server logs, there are always loads of requests from bots trying to attack Wordpress vulnerabilities in particular.