> As an example, instead of writing \(G = (V,E)\) directly you might want to write \(\graph{} = (\nodes{},\edges{})\)

This can be great for personal use, but it can be very bad for communicating with others; (a) you won't be able to write a paper with a co-author unless you agree on your domain-specific abbreviations in advance (and, if you think that's easy, then I say from experience that it isn't), and (b) most journals prefer a minimal number of custom commands, and some forbid custom commands entirely. Even if journals permit custom commands, the more you define, the more likely you are to conflict in some baroque way with their own style files.

EDIT: Also, even if you do this only for personal use, it can be very hard to go back from it (just search for TSE questions on macro-expanders; there are plenty, but all of them that I know of assume some well formedness constraints that make sense to their authors but will almost inevitably conflict with one's own ad hoc conventions).

In fact it's the only way to scale a paper across tens of pages and over multiple people