In the 70s it was actually easier on second shifts. People played the same areas of the lane and the balls tended to track the pattern not bkow it up. Things started to change with the introduction of urethane balls and limited distance dressing. Allison shot his 900 before the limited distance rule. The rule still in effect then was that oil had to be applied evenly gutter to gutter. If there was a perceptible build up toward the center it could be called illegal. Comparing it to modern rules, some sport patterns wouldnt ve in compliance
I guess we have a different memory of the times.
In the early 70's were with rubber and plastic balls.
The lanes had lacquer finish, which was a soft material, and oil would settle into "dimples" in the finish. Due to the softness the ball track would create a depression in the area most used, which was a fairly straight line towards the pocket.
The depression would effectively help guide the ball towards the pocket if you got the ball into the groove. If you played the wrong angle, you would pass across the groove with no help from it. You could hook the ball, but again no help from the groove.
To be competitive with the best at that time, you had to use the groove, which meant "straighter is greater"
Also at that time, left handers didn't "dominate" because they didn't build a groove on their side.
Then along came water based urethane lane finishes.
It's a harder material, without the "dimples".
The common complaint was that the oil moved around on the surface too much.
The real issue was the ball didn't create the depression towards the pocket, so "straighter was just straighter" and people who chose to hook the ball could become competitive.
Left handers became more competitive because of the help taken away from the straight right handers.
Bowling ball companies decided to "help" the straighties with urethane which accepted sanding more effectively than plastic. Urethane allowed the "dead handers" to get the ball to find a little friction and generate a bit of entry angle.
At the same time, the "live handers" benefited from the additional friction as well.
To put it on a scale, the coefficient of friction of a plastic ball to dry lane was something like 0.12, and urethane was something like 0.14, while resin is something like 0.26.
When Allison shot 900, it's true, it was before limited distance dressing, but limited distance was ABC's response to proprietors and the walled up lane conditions so prevalent during the days that Allison shot 900.
Somewhere in the 90's ABC/USBC gave up on oil pattern rules which opened the flood gates on honor scores.
With the current set of rules on oil patterns, and resin balls, it appears bowling is back to playing the groove (created by oil, and dry boards) and still get entry angle due to the resin balls.