And how many entered from 1970-1974? I believe that would be two and the difference is statistically irrelevant. If the gameplay was more defensively oriented through the 1970s and 80s, we would have more HHOF goaltenders. The wide-open play of the era certainly reflects in the bias against netminders throughout that period.
A number of players failed to make Junior 'A' teams and then went on to play in the NHL throughout its history. This is simply grasping at straws. Garry Monahan was drafted first overall at the age of 16 by the Montreal Canadiens in 1963. He went on playing Junior 'B' the following season. That sure doesn't speak well for the depth of that era either.
Some earlier thoughts of yours from 2012:
Junior B Players In The NHL
Your quote regarding the US high school players:
Another earlier quote of yours from 2012:
Junior B Players In The NHL
Conceivably, you should equally apply this line of reasoning to the burgeoning US junior program during the 1970s-80s? Some of those high school teams were more akin to existing Tier II Junior 'A' and 'B' teams during that time, as The USHL was just commencing its junior operations in 1979-80. Most assuredly, if the US hockey program was further along during the 1970s, 18 year old American high school kids would have played in the NHL if they were eligible. There were certainly enough roster spots available for those 18 year olds during the 1970s but they simply weren't eligible to be drafted.
On that note, perhaps you find it a bit disingenuous to leave out the fact that 20 was the minimum draft age until 1979? I undoubtedly do. I find it equally duplicitous to insinuate they were 'mid-level' high school players as that is just patently false. Perhaps next, you'll declare they were searching cities during the 1980s and grabbing players from Midget House League?