The two most common sources of bloatware I saw when I was using Samsung phones were: AT&T and Samsung. Not only the number of bloatwares is crazy, they keeps coming back (from OS update?).
As a samsung user i can confirm this , maybe it has its own contribution to competition, but i dont see any excuse creating and dictating your own ecosystem for every single bit of mobile functionality but i am pretty sure its not limited to samsung. Also what is wrong in my opinion is that they do prevent flashing stock images
Samsung doesn't want to be dependent on Google for a core business. They are hedging their bets by building out a parallel ecosystem to enable a future switch to another OS.