What PHP added was primarily ease of use with the ability to deploy code simply by creating a single file, suitable for mass deployment at ISPs in the era where everyone used shared servers, and the combination of comparative ease of use with enough performance to do serious projects. Cold Fusion was also easy but didn't support things like persistent connections (read: order of magnitude slower) and the core language was very, very slow and also quite limited and buggy. You could find much faster options if you wanted to build, debug and deploy a conventional language like C++ or Java but the cost and risk was so much higher that this was unfavorable unless you really needed performance.
EDIT: if you want a snapshot of what the 90s web was like, http://philip.greenspun.com/panda/ was quite popular in the day. I know at least one well-known business which still has a revenue-generating website built in TCL, too…