A lot of us (like me) are old enough to remember how this actually went down. Just because VCRs existed in the late 70s doesn't mean a lot of people had them. It was the same with the first wave of home computers. They were pricey and there were only a small number of early-adopters.
VCRs didn't begin to get affordable until the early 80s, like 82-84. Also, commercial tapes were sold for $79+ in the early days. That was a lot of money then. The home video market only took off when the industry finally decided to lower prices to around $30. The video rental boom soon followed. Many films were held back from home video for a long time as well. Star Wars being the most famous example.
The first tape I actually bought was Wrath of Khan, and I darn near wore it out.