A single-person “solopreneurs” do not necessarily need a website. They usually do because this helps their marketing efforts (and that’s what customers look for while doing the due diligence).
Larger firms — 99.999% of them have websites. We’re living in 2019 after all, this is the main place anyone would look at for news, contact details, team information, possibly industry information or additional resources, and much more.
There are certain exceptions, such as restaurants or coffee shops. Most of them do just fine on Facebook, Google My Business, and other local listings. A website may exist but it isn’t really critical.