And there are gasses other than Oxygen that can make flames. For instance look up youtubes of Hydrogen & Chlorine flame. So even if flames are necessary, I'm not convinced that Oxygen must be necessary.

Yeah, I don't see any inherent reason why you couldn't use wind/water/geothermal/solar energy and then electricity to get as far up the tech tree as you like. Or just some other form of chemical energy. Some of the steps sound more annoying or slow, but unclear why they'd be blockers.

> but unclear why they'd be blockers.

Something doesn't need to be a blocker in the small to be blocker at large.

I.e. anything that introduces more friction, or is less efficient, for making progress could hamper technological accumulation.

Clearly for general life on Earth, water was a tremendous enabler - although surely other forms of life without water must be possible - but perhaps much less likely.

Likewise for technology, fire is a tremendous enabler. So much of chemistry and material structure is temperature dependent. Not having a similarly flexible way to adjust heat over a wide range would make vast categories of advances too costly to be immediately beneficial, and therefore much less likely to be explored.

I agree. It's an interesting rationale but statements like these feel biased toward our own human-centric history: "on worlds with oxygen abundances less than 18%, technology will not be possible".

I'm not convinced a clever species couldn't find another route.