Besides all that others have said, this is a very risky gambit to pull off. You need to be certain that you have a lot of support already, or they can just take you on your word and let you resign, and there’s not much you can do.

One good example of this backfiring is when Brazilian President Jânio Quadros renounced, which is generally believed to have been a power-grab move with the military, but was accepted by the Congress without much hesitation.

This triggered a political crisis (in particular due to the leftier leanings of the vice-president), but restoring Jânio was never an option.

So even if Stalin was testing his support, the support still had to exist and be reliable in the first place.