Machjo, our Westminster system of governance would function questionably at best without the use of legally-recognised political parties. For one, how would we ever know who forms the Government of the day? Would everyone except for the ministry be the Opposition? How could someone be a prime minister if there is no ‘largest party’ in the House of Commons? Jurisdictions without political parties are rare, and those that do exist do not function in a way that a legislature should; the Legislative Assembly of Nunavut comes to mind.
What? Could Parliament not elect a Cabinet? Essentially, it's assumed that the party members are voting in favour of their leader to be PM. Without a party, that assumption cannot be made of anyone and so an actual vote would have to occur. My guess is that better-known MPs are likely to win since they'd be... better known. This could also provide stability, and also an MP who's won a few times is likely doing something right at least.
And as for 'opposition', the problem with the current system is that we send the message that those who are not members of the governing party have opposition as their mission statement. Oppose, just oppose, oppose anything even if you agree with it, but just oppose. And those who are members of the governing party are to defend, defend, even if they disagree, just defend, and blindly defend. It's like kids in a the schoolyard playground.
Instead, without parties, those who agree with the government on a particular policy proposal would defend it, and those who don't, wouldn't. Nobody would support or oppose like blind bats just because that's their job. They'd support or oppose with an understanding of what the hell they're supposed to be supporting or opposing. As a result, any support or opposition would be genuine and purpose-driven rather than to score brownie points for the party. Politicians are not to be equated with hockey players for cryin' out loud.