[phao]

Directly, I believe this has more to do with people interested in the language seeing it being used in actual projects.

Indirectly (a lot indirectly), sure. Maybe the software should perform better or maybe have fewer bugs because programming language X or Y is understood to help with those things. Maybe it showcases a more flexible architectural design, which leads to more potential features in future versions, etc.

[galangalalgol]

It also hints at the mindset and values of the creator. Communities around languages value things that may or may not line up with the qualities of the language they form around, but simply the fact they value those things is reflected by rhe things they produce. If people think a language is performant, then performance will be something their community values. If it is known for having a learning curve, their product might too.

[acje]

A bit like seeing «car built in carbon fiber”. May poke the interest in materials or imply different quality attributes and design intent.