Well, people using smartphones never really had much choice about using Webkit, considering the fact that Apple and Google forced them being preinstalled, and Apple disallows any other rendering engine still as today. Nor most would care anyway about the engine, they just want to get the stuff displayed right, and since Webkit/Blink becames the mobile de facto standard by market share, and mobile first is our reality in terms of web sites, it is the standard engine being used by the vast majority.
For the other part: competition is good, it brings up new ideas and concepts into working products.
For example, when GCC development became stagnant, EGCS was born, which was a fork, brought in new life, ideas and so on, so GCC went from stale to thriving - until both projects merged. Nowadays the competitor is LLVM.
Or when glibc-development became meh, eglibc came into existance.
Or just look at Sendmail, and what happened because of Qmail and later Postfix.
Or Apache and Nginx.
The examples are endless...