I think you overstate how bad said situation was, and to the extent it was a problem I doubt it had any meaningful impact on PC usage rates, and I have not the slightest doubt that such a situation would have had minimal bearing on smartphone adoption. People are drawn to things that offer utility to them, regardless of any downsides. That's why people will happily hand over the entire details of their private life to any internet service that asks it of them, and why the market does not punish any company that has security breaches and loses hundreds of millions of people's personal information. Security and privacy are at the very bottom of a normie's list of concerns in practice, even if they might say they care in surveys. If something is useful to them, they will use it regardless of security and privacy flaws.

Edit: It's also telling that you need to go back to XP to make your case. It's 2025. Security practices have improved a ton to give people more protection from themselves without outright taking away their freedom to make choices.

Also, let's again re-iterate that Android usage outnumbers iOS by three-to-one, so it is clear in practice that people are in fact willing to adopt a phone that allows them to make mistakes (if they try very hard to).