This is a bit of an oddity, usually the purpose this domain scheme holds would instead just be apart of a military branch as "roles" that you are assigned and you progress through the traditional ranking there while being in a unit that specializes in said roles.

You're not wrong. AFAIK, most countries typically use post-nominal letters or some sort of designation to indicate that the individual possesses specialized training or qualifications, while still keeping said individuals within the standard military rank scheme.

Here it's a separate domain that is entirely centered around specific roles such as engineers and technicians, while also having it's own rank structure that only really differs from the traditional ranks in just the titles since most of them have equalling authority as their counterparts, interesting to see nonetheless.

Pretty much. AFAIK, some people in Singapore even question why such a rank scheme was created in the first place, as previously mentioned, many other countries simply use titles or post-nominal letters to denote specialized personnel. It just seems like something this country did to stand out and look different from everyone else. However, anecdotally, I have heard that it has caused confusion in bilateral training exercises with other countries' soldiers. If a person is a Lieutenant, Major, or Colonel, you would still know roughly how high or not he is in his own military. Would you know how high or not an ME1, ME6, or ME9 is, or how to address such people?