(meta-comment: someone keeps posting population doomerism to HN. Why do you think this is relevant, or that a trend dipping negative for a while will inevitably continue that way?)
Probably because it's presented as a problem to solve (we don't know how we're economically going to deal with it) and engineers love a challenge, even when they're not experts in the field. So same reason why urban planning issues, etc often show up.
Also because it’s essential to the older capitalist mindset of continual growth which drives the valuation of most tech companies. The idea of stabilizing on a smaller level has really fallen out of favor over the past few decades, but it’s an existential threat for companies whose shareholders are accustomed to double-digit growth.
Probably because it's presented as a problem to solve (we don't know how we're economically going to deal with it) and engineers love a challenge, even when they're not experts in the field. So same reason why urban planning issues, etc often show up.