I was at a startup from 2000-2003 where the chief scientist was a security wonk and demanded that our product worked with and without JavaScript enabled.
No wonder the startup failed. Imagine trying to make a useful product with one hand tied behind your back!
I just checked, Google and Amazon still work flawlessly without JS. And many other "useful products" too.
The question is, if a startup can't make a site that works without JS, are they actually focused on the product? Assuming it's not a webapp, of course.
You're making two completely different versions of your web product: one with a rich, modern experience using JavaScript and the other using vanilla get/post.
I've built several SaaS products and I can't imagine building a complicated product that supports both a JS and no JS version with a small, startup team.
It can go the other way, the CEO at one company I worked at demanded that we have a rich, dynamic user experience with real time editing AND we fully support all the browsers that had visited the site in the last 6 months. We had people using Blackberry, IE6, Opera, Konqueror and stuff you've never heard of.
They were happy to force javascript but wanted it to work on early smart phones.
The VP product was losing her mind fighting the CEO over this.
Bizarre. It's like starting a parking lot business by trying to accommodate every vehicle you see driving by your site over 6 months. You could have Winnebagos, tractor trailers and more bizarre vehicles, none of which you should consider as viable customers.
Well, maybe that parking lot example will help you in the future to explain why this is a dumb approach. Expanding the customer base has its own costs, so you obviously want to target some point of optimal return (revenue from customer - cost to support customer), otherwise you're just shooting yourself in the foot.
2000-2003 was a very different time, and people making javascript heavy sites then tended to be terrible. If I remember right gmail worked fine without javascript even after that time period.
With that attitude you likely were writing for IE5/6 only too. We're still dealing with the fallout from that 20 years later.
I worked for a company that had one user complain about the site requiring JavaScript, because he didn't "trust" us. Manager asked him why he trusted us to create an account on the site.
No wonder the startup failed. Imagine trying to make a useful product with one hand tied behind your back!