Anything that facilitates commerce makes it easier to monetize spam, just as it makes it easier to monetize porn, or even illegal activity (eg bitcoin). You can't really fault Google or Facebook for this, as soon as the internet moved away from hobbyists, academia, and scientists towards the general public, it was absolutely inevitable.
The only way to have prevented something like that would have been to make the internet a giant closed-garden AOL like system with total control over users, identity, and content.
Fundamentally, if you make something frictionless to join, you end up with parasites. If you impose a cost to join, you end up hurting average users, because it's hard to raise the price high enough to keep out bad actors, especially if the expected value is positive and high. (If I need to spend $5000 in order to get one sucker for a MAKE MONEY FAST scheme, it's still worth it)
Part of Apple's value proposition is a tightly controlled walled garden with a high cost to entry. If you're willing to pay those costs, you're protected from a lot of spam, at the cost of a lot of friction to enter the ecosystem, and the lost of full autonomy over your devices.