It's a feature of the parliamentary form of government (UK, Canada, Australia and others).
Basically, members grandstand and try to make members of the government (almost exclusively the Prime Minister or Cabinet members - who have to be elected members of parliament) look like idiots.During each sitting day at approximately 2:15 p.m. (11:15 a.m. on Friday), the 45-minute Question Period begins. At this time, the Speaker recognizes the Leader of the Opposition, or the lead questioner for the Official Opposition, who then asks a question. This lead question is usually followed by others, called “supplementary questions”, which in most cases seek clarification of the answer to the initial question or attempt to obtain further information.
Throughout the remainder of Question Period, other Members representing the parties in opposition to the Government continue the questioning. In accordance with an agreed-upon rotation, one or more other of these Members may also be entitled to ask supplementary questions.
Losing official party status means that they can't ask questions. Which means that they don't get media coverage and are doomed to appear irrelevant. Say there's a scandal involving the party in power. The good footage is always of members of the opposition acting aggrieved during question period. No questions means that no one sees your "outrage."
Parties do come back from losing official status. But it can take a while or in the case of the federal Progressive Conservative party who went from 156 seats and a majority to 2 seats in 1993, it involved the party basically being absorbed by another party before rebranding and coming back into power 13 years later.