You don't accept it, since you don't accept 0.1r is a valid decimal form of the fraction 1/9, or that 0.3r is a valid decimal form of the fraction 1/3.
If you don't accept these, I can understand completely why you wouldn't accept that 0.9r = 1. Perhaps you should read the Wikipedia article. It cleared everything up for others, so it should for you.
Possibly a humourous note, but as Randall Monroe (creator of xkcd) noted, the only debate on Wikipedia concerning 0.9r = 1 is whether the page on 0.9r should be merged with the article on 1.
If you don't accept these, I can understand completely why you wouldn't accept that 0.9r = 1. Perhaps you should read the Wikipedia article. It cleared everything up for others, so it should for you.
Possibly a humourous note, but as Randall Monroe (creator of xkcd) noted, the only debate on Wikipedia concerning 0.9r = 1 is whether the page on 0.9r should be merged with the article on 1.