I think it's still true. Bootstrapped businesses need to bring in money to pay the bills. They can't just dump VC money into growth. Sales is just as essential if not more with a bootstrapped business.
How significant would this be if you have nearly negligible running costs (beyond say the cost of registering a business and renewing it)? Starting from a semi-hobbyist position where I would be the first client (think something like the stuff on Hackaday or tindie), I'd imagine nearly zero other bills. (I'm talking about a very low volume, building-in-your-garage type of thing.)
At some point you'll want to switch from sales-led development to establishing product though, otherwise your product will simply be a hodge-podge of feature requests meant to satisfy individual clients with no real cohesion, especially if you want to go self-serve.
Unless your startup is intended to be more of a boutique consultancy and not some kind of SaaS.
If you're shopping for a high performance $10,000 oscilloscope or 3000 high endurance SD cards a month for the next 12 months, or a point-of-sales system for your small business?
Then the suppliers will have a sales person who'll visit you, demonstrate the oscilloscope's features, offer to loan it to you for a month or two so you can try it out, chase up answers to technical questions ('Can I install antivirus software on this oscilloscope?'), and suchlike.
If you're selling into an industry where that's the norm, you're probably going to need someone who knows how to do it :)
