It is a wrong claim. Fragmentation is so high that it does not even exist a referring HW platform for each smartphone vendors. Very small smartphone producer can claim to have such platform: fairphone, pinephone, murena, librem, someone else?
However, it does not exist because the revenues-market dynamics. The good news that offering a new way in doing business and collect revenues, the fragmentation will be reduced in time because it is a cost for everyone. For someones is a way to collect revenues. Hence: fragmentation costs + its benefits is still positive. Offer them a way to cut fragmentation costs and increase revenues, and they will embrace it as soon as they started to understand it.
More or less, the innovation lays here. Whatever, ASOP or CentOS.