

It just hasn’t hit that Twitter-level critical mass of users
Twitter used to be bigger than it is now and it also used to have less spam. So clearly size isn’t the problem.
The problem with twitter is Musk fired all the people who spent their day figuring out how to hide (or just delete) shitty content.
First of all, you’re implying it runs latest Windows - but Windows 11 shipped a few years ago.
Second - not really a fair comparison. 18 years ago the iPhone didn’t even exist. And the oldest model (17 years old) had really weak hardware. 4GB of storage, 128MB of RAM, and the CPU was an order of magnitude slower than current spec CPUs (it was also 32 bit - and 64 bit ARM is a completely new architecture - similar to the failed Itanium).
Even if it was supported, it would be a horrible experience.