It'd not even be hard for them to stop it, but they just had to be annoying instead.

When I first started out on the internet, ads were banners. Literally just images and a link that you could click on to go see some product. That was just fine.

However, that wasn't good enough for advertisers. They needed animations, they needed sounds, they needed popups, they needed some way to stop the user from just skimming past and ignoring the ad. They wanted an assurance that the user was staring at their ad for a minimum amount of time.

And, to get all those awful annoying capabilities, they needed the ability to run code in the browser. And that is what has opened the floodgate of malware in advertisement.

Take away the ability for ads to be bundled with some executable and they become fine again. Turn them back into just images, even gifs, and all the sudden I'd be much more amenable to leaving my ad blocker off.