[pdonis]

> there's no issue

There's no issue as long as you think that "adding in scalar (and possibly vector) terms" is somehow a "simpler" change than "adding a new kind of matter".

But when you look at what "adding in scalar (and possibly vector) terms" actually means in GR, it's the same thing as "adding a new kind of matter". You're just calling the new kind of matter a "scalar field" (and possibly also a "vector field", i.e., two new kinds of matter).

In other words, when you take relativity into account, "MOND" is not an alternative to "dark matter"; it's just one particular way of adding "dark matter".