Simply because Americans cant understand letters with umlauts can be treated as entirely different letters.
It would almost be like if Yulia Lipnitskaya became Alia Lipnitskaya, as an example. Ye, yo, yu, ya etc., same set of symbols.
The worst example of this nonsense is swedish å being transliterated as a, when it is just simply an o and o only. Almost as bad is the ae letter that just is ä written differently, actually split into a and e even though it has no hint of an e sound.
Like in Finnish with a and ä, I am sure Russians can understand when to say ye amd when yo, but for transliteration as pronunciation guide for people completely unfamiliar with the language, it is a terrible idea. And really, while I am sure she is used to it by now, I still find it quite disrespectful to not pronounce names properly.
Yes, with sounds that dont really exist in the language like Shch vs Sh I understand, but when you can make all the sounds, at least make an effort...
The only sound I have found to be just impossible to get right is the korean HH I believe.
Sorry for the lengthy rant. -. It is an important topic to me. Especially for a name as beautiful as Aliona.