Those are open-source frameworks, which is antithetical to competition. The whole point of open-source is that the contributions of one entity can benefit everyone, while in this situation, having so many frameworks "dilutes" the efforts because the same problems need to be solved in each framework. Smartphone makers aren't here to share their technical advances with everyone, they're here to make money.
I'm not saying we should purposefully agree on killing all but one framework, but the ideal situation is if one or two come out at the top as being just the best in their category so that everyone just use them, and all efforts converge towards those.
I don't see "open-source" as being antithetical to competition, at all. In fact, e.g. Databricks only exists because of Spark. There is competition in the open-source world too, and IMO that's a good thing.
That assumes you can have a single framework with all the features people want without causing issues (conflicting basic designs, high cost to maintain, deployment costs, configuration costs, etc.).
> I believe it drastically reduces adoption of these tools
As does any competition. Tons of smartphone makers = less adoption for any one of them - and many will close down. Still not a bad thing.