In the 90s? There weren't any. You just had to put up with it.

Wikipedia says the first Adblocker was released in 1996, but I never heard of it, nor did I know of anyone who was blocking ads back then. I didn't hear people discussing Adblockers until the mid-to-late 2000s, when AdBlock Plus first became popular.

I used ABP for many years until I learned that they sold out to the ad companies, and thus switched to Ublock Origin sometime in the 2010s. Not to mention that I got tired of having to manually update my ad filters. UBO made adblocking simple with its auto updater.