I'd reply as I think Thomas Sowell would, with his standard question "compared to what?"

Compared to what is democracy a poor form of government?

Sure, sugar gum drop trees won't spontaneously spring out of the earth when people get the vote. Nor is the vote an automatic cure for your aunt's gout.

And there are plenty of failure modes. The particular ones you show from European parliamentary democracy are not surprising to me, as an American with a preference for the constitutional republic we nominally have here.

The key difference seems to be attitude toward government. In the US originally, and to some degree in pockets still, the federal government, and government in general, is seen as empowered with authority to secure your rights. Not positive rights to the fruits of the labor of others, but negative rights against abuse from others. From the Declaration of Independence:

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.

That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed,

This model of government does not include a "goodness generating machine" as one of the deliverables. Government exists to protect your "inalienable rights", such as life, liberty, and pursuit of happiness. It is not a happiness generating machine, which will fedex you monthly packages of happiness, it is a machine to protect your freedom, leaving you free to live your life and pursue happiness. You are the happiness generating machine; it is the freedom protecting machine.

This model has it's own failure modes, such as when much of the populace starts wanting the government to be a "goodness generating machine".

And it's not a perfect machine even in a society of people who support it for it's original purpose. Inevitably, those controlling the levers will exercise that power for their own interests, while the general population will have both limited knowledge and incentive to properly watch over them. "The price of freedom is eternal vigilance." That's an expensive price, suffering from free rider problems, so we should always expect some abuse of the system.

Wah wah wah! I can't have all I want for the price of wishing for it!

So? It's worked pretty well, and I'll take it over the Gulag or the Great Leap Forward.

If you have a perfect machine handy, I'm all ears. The historical alternatives seem vastly inferior. So again I ask, compared to what does democracy suck?