A reasonable amount with reasonable placement.
I... don't think we used the same internet. There were pop-up ads, pop-under ads, flashing ads, "you're the millionth visitor" ads, "hit the monkey" ads, ads with sound, ads with drive-by ActiveX malware that'd silently install onto your PC and use your modem to call premium phone numbers (to make money for the scammers) while you were asleep, ads that popped up "Windows messenger" alerts, ads with malware that phished bank details (when nothing used SSL and before 2FA was a thing), etc. You may have just forgotten about this since it's been a loooooong time :)
Ad networks like Google AdSense/AdWords were a huge improvement over the garbage we used to have to deal with. At the time, they were just basic text ads or 468x60 banners (which is a long-deprecated ad size now)