No. Although there is a fuzz around head shops these days, mainly due to the legalization of cannabis, cigarettes and tobacco products existed long before head shops appeared, being sold in other types of places, such as liquor stores, coffee shops or smoke shops.
Nowadays, you can find tobacco products in Denver head shops, but not exclusively there. Many other stores sell them, especially vape pens and smokeless tobacco products that seem to be very popular.
Some of these products can even be bought from retail stores that are not necessarily specialized in selling tobacco products. However, there are some strict rules that these stores must comply with, considering that they are not adult-only, like head shops
The FDA forbids, for example, retail stores to sell cigarettes and tobacco products in a vending machine or self-service display. Also, they are not allowed to sell flavored tobacco products (except for tobacco or menthol flavors).
Retail stores are also not allowed to offer free samples of cigarettes and tobacco products, or to display advertisements for them without a warning statement.
Retailers have their role in protecting young people who visit them, and these legal requirements are designed to make cigarettes and tobacco products less attractive to them. Considering that head shops are adult only, these requirements are different.