On the one hand, I see your point; hacking it together probably isn't hard.

On the other, they're a startup with limited resources, and time to market matters dearly for them. They probably don't even have product-market fit yet, and supporting Microsoft technologies that Microsoft has abandoned seems questionable.

Anyway, I upvoted your comment, because it could be that their target market is running in weird enterprise-y environments and your problem is common. Feedback is helpful and hard fought at small companies.

(No affiliation.)