I recently saw this question: What are some standard monsters or NPCs that can dispel magic?
It is, of course, a list question, and it isn't particularly narrowly scoped. List questions are often too broad and it is often difficult to say which list is the best, and so most list questions are bad questions.
5e hasn't been out very long. As a result, there are actually fairly few monsters published that can cast Dispel Magic. Miniman's answer there, I think, covers all of them (not counting spellcasting demihuman NPCs). That answer is less than half a page long, well within our limits for reasonable length.
5e is a game published by a large publisher with a history of producing a lot of content for its supported games. There is no reason to think that such content will not be produced for 5e, just as it was for 4e, 3e, AD&D 2e, AD&D, D&D basic, etc.
If more content is produced, the answer will be outdated, which is fine because the question will still be useful. However, it will likely not be long until the 'correct' list answer is too large and the question thus becomes too broad.
How should we handle questions like this, that are fine now but will likely become poor in the future?