For the record, I believe it's a reasonable position to take to say "it's tougher to win a WS now than in the past. You have to win more series."
Conversely, one could reasonably believe it's easier now. Much eeasier. You need a chip and a chair. Teams used to have to win their respective league to have a shot at the WS. I'd say beating the entire AL over 162 games is tougher than finishing as one of 3 division winners or the 3 best also-rans.
The 1987 Twins had to win the ALW, one of 2 divisions rather than 3, and there were no extra chances awarded to 2nd, 3rd or 4th place regular season finishers. The 1987 Blue Jay's won 96 games, losing the ALE to Detroit on the last day of the season. Do you suppose they'd say it's tougher now to win a WS?
You have to get in the postseason to have a chance. The postseason might be tougher. Getting there is certainly much easier.