What makes you think that "no one had objections about Apple and Amazon doing so"? Lots of people did. Lots of people have been quite vocal in their dislike of the so-called "walled garden" practices of various organizations.
Google and Android have generally provided a relatively open third-party alternative to what Apple and others are offering. If the degree of openness is changing, however, then I can see people speaking out against them, too, and possibly looking for alternatives.
Google and Android have generally provided a relatively open third-party alternative to what Apple and others are offering. If the degree of openness is changing, however, then I can see people speaking out against them, too, and possibly looking for alternatives.