When I was young, computers could only be accessed within well defined institutions (like university computer centers), with approved software. But then personal computers became available, and pretty soon we were all computing promiscuously, at home and in the office, with third party software (unless we were Apple users, in which case we still used approved software). And computing wasn't just for data and work anymore, it was also for fun, something you could do spontaneously.
The internet only accelerated things. Old barriers broke down.
Then came viruses. Strange software wasn't safe anymore, you could catch something that could really harm you. And you could pass it on to your correspondents and collaborators if you were infected. You had to be careful with whom you traded bits and bytes.
Today Apple is back in vogue; iPhone apps are approved software. We all have virus scanners, and our IT checkups may now include routine tests for infection. Our junk mail filters try to protect us from inappropriate contact. We practice safe computing.