I don't support the principle at all, but this would probably have been a stronger & better Bill had it been a Govt one (it would have had pre-leg scrutiny for example), and it would have had all the parliamentary protections that come with a Govt Bill. But it isn't & we are where we are.

It's our parliamentary & constitutional arrangement that a Bill has to go through all stages in both Houses to become an Act. In the case of disagreement the Parliament Acts can be used. You can call it what you like, but you can't simply set it aside because you are for/against a particular issue.