because they were not integrated in the operating system [1] and/or the OS were not sandboxed.
Also, app stores did not exist, app stores do scan software for malwares, they are actually antiviruses on the cloud.
but it's an opaque anti virus, not under the user's control, apps could be rejected for whatever reason, so today chaos is only hidden under the rug, but it's actually worse then it was before.
Nobody back then said: "my grandfather should not use the computer, he's in danger", also because if someone owned a computer back then they probably knew how to operate it, today that's not true anymore by a large margin.
My comment was a bit ironic and maybe low quality in that sense.
They wouldn't be needed if there weren't malware chaos in the first hand.
So people were willing to pay for removing malware and keeping their computers safe because the threat was real and common.
It is true that there is still a big chaos, but it is hidden under the rug.
Well, my first computer was a Commodore PET, so I was there before, during, and after. Don't you think iOS with "side loading" would be more like MacOS in 2023 than Windows 98?
Of course it has caused chaos on desktop platforms, especially Windows in the early 2000s, late 90s.
Since that era, it’s slowly dug itself out of that hole.