I understand, although a lot are doing both.
It's true that quite a number of dotcoms had untenable business models although quite a few have worked - Amazon being a classic example. In that scenario, in the U.S., Barnes and Noble was a case in point of a bricks and mortar outfit who initially refused to have anything to do with e-commerce. They lost business hand over fist. Now they have recovered somewhat, but were slow to realise the impact of the internet. In our geography, WHSmith would be an example except that their shop business has been a cockup for 20 years or more anyway.
I completely agree provided that the product or service is worth having and differentiated in other ways as well.