Yes but "talking to your customers" is universally applicable and valuable advice. One could argue that it's of even greater value if you're targeting a niche with only "a few customers" because you need to ensure you really deliver enough value to get them onside and paying a rate that ensures you generate a profit.

I think most small companies were talking with customers for long time. The challenging part of this advice is talking with your customers at scale and separating signal from noise.

The article even specifically suggests having fewer, better customers.