A paginated inbox can be extremely useful. Pagination gives you a "You are here" context: you are on page 3 of 20. That context is great in use cases such as "I need to review everything in this Inbox". If you just finished 3 of 20 in that case you know you are roughly 15% done. If for some reason you are interrupted and need to close the app and come back you know that you can probably start right where you left at on page 4 of 20.
Finite scroll is a compromise that you get some amount "you are here" context from scrollbar thumb size and position. If you are interrupted you can generally visually guess about where you left off, maybe.
Infinite scroll is terrible tool for an inbox because you no longer have such context. Scroll too far and the scrollbar thumb changes size because new items came into view. Most infinite scrolls entirely hide the scrollbar thumb because it is precisely so useless. Try to resume where you were in your inbox after an interruption and you have no idea how far to scroll down, and you can't just use the scrollbar thumb and hit an approximate spot. You have no context for where you are, you are lost in an infinitely scrolling maze of items all alike.
Even if infinite scroll wasn't a dark pattern (and it is, there's enough behavioral psychology studies now that have gathered enough evidence that infinite scroll feeds addictive behaviors), it is a terrible tool to work with if you are trying to get stuff done. It has none of the context of "you are here" and "here's how you can come back to where you were if you need to leave". Both of those things contribute to why it is such a dark pattern. Both of those reasons are strong reasons why it is an anti-pattern anywhere you expect people to work/to get stuff done. Pagination is great for getting work done and infinite scroll is awful. Finite scroll is alright compromise between the two for some apps.