From what I understand, which is admittingly quite tiny...
So now we're looking at the following scenario:
- Italian President appoints former IMF exec as PM considered 'ok' by Brussels, Merkel and financial markets
- New government has no majority in parliament and has basically no power to do anything but keep the books in order until a new election can take place
- New elections are organized to break the 'stalemate' so a government can be formed
There's two "stalemates" neither one of which an election is needed to allow a government to form. (Assuming they don't give up and accept Cottarelli.)
The simple one being discussed above which merely needs a new anti-EU President in office so as to not block anti-EU ministers. Easily solved as doing a joint sitting and kicking him out for "high treason" and/or "attacking the Constitution", you only need a majority vote, which they already have. (Sure, that's not how the old establishment parties would do things, but they're bad and why we elected Lega and M5S in the first place.)
And the larger one in which the "populist" anti-establishment parties that are running against everything bad are being forced by the inherent nature of things to start picking things they're actually for and forming ministries and so on. That's what I take as the primary reason Grillo bailed out on his own movement. It wasn't supposed to get involved too much in that nasty politics stuff, just oppose the bad things until things worked out and were good. But that too was already solved
through politics and is actually probably
threatened by an election. Lega increasing their vote share doesn't do anything really, especially if it's taking the anti-EU half of Forza from Forza. If anything it probably threatens the current on-paper agreement by increasing Lega's share of the M5S-Lega coalition with members who probably don't agree with M5S on anything except how much they dislike the EU and foreigners in general.
The Italian system has changed back closer to how it was before 1993, a government can fall without losing confidence and triggering an election as the "first party" no longer is guaranteed a majority of seats. (The entire reason there even is a coalition government discussion this time.)
Just as an example using no support parties or absolutely zero hyperbole. Lega plus M5S is 352 seats, ~55% of the house. Say, M5S is actually a Holodomor movement in disguise except they hate the EU. Once they and Lega withdraw from the EU and build a wall around Italy, M5S can break the coalition, enter into a new one with the "Left coalition" which is 349 seats (assuming they don't get the 14 "Totally Not Communists" to join in), this is also ~55% of the house. (~58% with Free and Equal) They can then go on to nationalize the entire nation's means of production. Lega and the rest of the Right coalition can't do jackshit about this until 2023* as long as the alter-coalition holds confidence.
*Assuming the M5S-Left simply don't
repeal elections democratically withdraw non-Marxist parties, of course, before ordering the Ukraine into famine conditions.