For me, pluri-selected candidates sound a unique aberration. Some other elements of why the Italian election system works as bad as it does exist elesewhere, though not necessarily as a problem.

Lots of small parties allowed by a lack of a 5% limit can be a problem (Poland) or not (Netherlands, some Scandinavians, New Zealand?). Pre-lection coalitions are limited in various ways in most proportional-voting countries, e.g. a higher percentage threshold or you must form an actual party union. But that big loose pre-election coalitions of a lot of smaller parties can, and for power must, be formed may happen elsewhere (France, at one point in Slovakia, in a way Spain), but the trend (and pressure) seems to be strongest in Italy, only I am not sure what makes a difference. Two political blocks (be them big tent parties like in the US or coalitions like you have) are usually the result of winner-takes-all, not proportinal elements of election systems (e.g. when there is some extra gain in becoming the biggest party/coalition), the need to bring in splitter parties to gain majority doesn't require more than the formation of smaller pre-election coalitions (miriad of examples across the new EU members).

Assured seats on party lists is a standard feature of proportional voting (of which I am an advocate), and one often held against it. But this is counteracted elsewhere when there is a choice of more than two parties, and (less often) when a wide party base or voters themselves are given some say in which persons get elected (single tansferable votes from Ireland through Hamburg to Australia, parallel direct and proportional voting as in Germany, local primaries).

_{*Lunatic*, n.
One whose delusions are out of fashion.}