My feeling is that it is indeed worth it to be pedantic about these kinds of best practices in a start-up. In fact, when I left finance to join a start-up, literally the whole reason for doing so was that the start-up was supposedly a place where engineering best practices are valued more than incremental short-term business progress, in contrast to the stodgy bureaucratic finance firm where political in-fighting prevents best practices from materializing.

I don't personally see any reason to believe working for a start-up could possibly be a good idea otherwise. (And since most start-ups only pay lip service to supporting best practices, while really supporting only short term incremental business gains like any other kind of organization, this is generally a good reason to default to believing that it's a bad deal to work at any given start-up.)

For me, this also has a lot to do with vision and consistency. If you create a start-up and your only goal is to sell it (or, more realistically, you are expected to do this because it is the goal of the VC firm you got into bed with), then you're not only not going to focus on best practices, but you're also going to jettison any part of your mission or vision any time it's not convenient to some incremental short-term growth opportunity. By the time you reach a point to sell the business, it may be completely unrecognizeable from the vision you started with.

If your only goal is to make money, this might not be a problem. But probably not very many people who agreed to work with you will share the feeling -- and they certainly won't stand to make meaningful amounts of money -- and so they are unlikely to be happy workers through most of the process. That means you haven't been getting their best effort all along, and the product is probably shoddy.

Generally (but not always), good engineers don't want to work for something that is explicitly a hype machine where maybe later quality will be hacked back into it, but probably not. So start-ups that fundamentally take an approach of short term product-market fit are pretty much by definition staffed by bad and/or unhappy engineers.

Contrast this with something like 37Signals/Basecamp. Of course they had to make engineering sacrifices along the way and didn't always do everything in some pedantically best-practices-adherent way. But their ethos/vision was to be much more about best practices than about unreasonable growth or winning an acquisition lottery. Yes, they were driven by succeeding with product/market fit, but they didn't ever become a slave to it or turn into zombies about it.

Given that there's such a poor success rate among start-ups (a large base-rate bias towards failure mode), it's hard to draw much from outliers of any kind, whether they are like 37Signals/Basecamp, or they are like some always-pivoting shop that always favored short term business gains but still succeeded despite it. But my perspective is that it's way, way better to be on the side that pedantically clings to an engineering vision and has a general ethos of turning down short-term business gains as a means of investing in longer-term best-practices-focused infrastructure.