Which Might and Magic universe are you referring to?

If you delve into the storyline of all the games, there are very few unclear or illogical moments. There is a clear (and, I must say, very interesting and originally designed) backstory, as well as information about the culture of most peoples, and the history of kingdoms, etc. I'm not arguing, there are some contradictions, but they are very few, and they are found to some extent in almost all fiction universes.

Regarding specific examples, the origin of the Confluence as an alliance of four elements from the Elemental Planes, which came to the aid of Erathia against Kreegan and the Blade of Armageddon, is more than clearly described in the "Blade of Armageddon" campaign.

Portals in HoMM4 - yes, it's a deus ex machina, but here the criticism is more generally directed at the VERY stupid idea of the Reckoning, which ended the existence of Enroth and all the promising plot lines that existed there. And the portals themselves quite organically ensured the arrival of the survivors on Axoth.