Close-voter here. I can't comment on why others chose to close the question, but here's my rationale.
Questions asking for the "advantages and disadvantages" of something are always suspect, in my opinion. Whether a particular feature of something is an advantage, a disadvantage, or irrelevant depends heavily on the asker's specific situation. In a large majority of cases, the question would be better if it focused on that situation and the effects of the subject on that situation.
Expanding on that point, another problem that can show up with "advantage/disadvantage" questions is that they can end up being too broad. Usually, there are many possible advantages/disadvantages that could be listed, most of which, from the asker's perspective, would be considered irrelevant. To give an exhaustive answer that describes the advantages and disadvantages from a fully general perspective is often difficult, long, and not all that helpful.
In my opinion, the question would be better rewritten as one of the following:
- Will using phonetic notation to learn Mongolian interfere with my understanding of Mongolian Cyrillic?
- Does using a strictly phonetic notation help with learning pronunciation better than using normal spelling?
- Will using a Latin alphabet-based phonetic notation interfere with my learning of unfamiliar phonemes (in Mongolian)?
TL;DR: Advantage/disadvantage questions depend heavily on the asker's perspective, and would usually be better if they focused specifically on that perspective.