> Granted, even in the 1990s there were ads;

the ads in the 90s were served by the same server of the site you were browsing. those ads were images. today's ads are from 3rd party servers running arbitrary JS code that the server of the site you are browsing knows nothing about how it works. ads from the 90s while possibly obnoxious and annoying were not able to be malicious as ads from today.