Probably because he went back on the deal that he made with Biden after the Debt Ceiling thing. If he had stuck to that, he might have gotten enough Democrats to vote "present" to have survived the vote.

But why throw any support to a person you can't trust?

This is a republican problem. They renegged the budget, they caused the shutdown, they ousted their speaker when he swerved to avoid it. The republicans have all the votes they need to not fuck over the constituents. All they have to do is their job. Dems know they won't do it. Every second republicans are burning political capital.

I think they decided that he is such an incredible piece of shit who stabs them in the back and reneges on every deal (see: his attempt on Sunday to blame the budget fiasco on them, his renging on the debt ceiling deal, his stance on J6...) that he wasn't worth saving. Either some R's join with D's to make a coalition (as just called for by H. Jeffries) or the R's have to get their shit together, painfully, for the budget. The last CR clearly showed the issue with the current R party composition. There is a wing that essentially acts as a third party spoiler. The CR was very much a win for the Dems (except for Ukraine funding, although I am of the personal opinion that a clean CR is the correct way to do a CR, fund other stuff separately).

Because he can't be trusted to share power.

McCarthy had two choices:
Do what the freedom caucus wanted and never see anything pass the Senate.
Make a deal across the isle and get some work done.

He dragged his feet, hymed and hawed and eventually caved in on option 2 as it's the only reasonable one.

Then he proceeded to attack those who he just made a deal with the very next day.

He could have instead said that real leadership is finding compromises that move things forward but he's lose MAGA voters who see the government burning down as an upside.

So he sold his soul, again, to those crazies and yet again proved he isn't reliable.

Does this benefit the House as an organization?

Absolutely not. But the clown show that will follow in the next few weeks will make the GOP look horrible at least.

And maybe, just maybe, some of the more sensible parts of the GOP will come to the Democrats with a power sharing deal that will completely neuter the freedom caucus once they see how hopeless their situation is.

What is the better alternative? What if there isnt a speaker by the time the stop gap measure expires?

I have this same question too, and - with all due respect - it would be nice if someone had a response other than blaming Republicans and just leaving it at that (I mean, it’s absolutely their fault, but it doesn’t answer the real question).

It would be nice to know Dems have a plan after taking this action. I’m fairly certain they do, but best I can do now is guess how it might play out. Not reassuring…

There is already a speaker pro tempore. The house can decide when it wants to elect another speaker, but business doesn't just suddenly stop now.