I'm not sure if it's true that the leader is less powerful.
In many countries, it seems that the leader has near total control over candidate selection, and dissent is punished ruthlessly.
In the US, it's easier for a member of Congress to openly dissent against the President's agenda. This was a major thorn in the side for e.g. Joe Biden.
Some Republicans today fear dissenting (though of course, most are enthusiastically on board), but I'm not sure that it would be any different in a place like Canada or the UK.
In many countries, it seems that the leader has near total control over candidate selection, and dissent is punished ruthlessly.
In the US, it's easier for a member of Congress to openly dissent against the President's agenda. This was a major thorn in the side for e.g. Joe Biden.
Some Republicans today fear dissenting (though of course, most are enthusiastically on board), but I'm not sure that it would be any different in a place like Canada or the UK.