It's pretty clear these modern Barca and Real teams are the most stacked in football history, just due to the sheer excess of funds and the lack of loyalty in top young players today in staying at clubs long-term. Did stacked teams happen in the past? Sure.
But if you were right about Ronaldo and Messi being the most dominant players of all-time, completely unstoppable, and a clear cut above anyone to play the game before, they'd have done much better for their national teams. Their goal-to-game ratio drops by more than 50% when they play with their national teams without these incredibly star-studded line-ups. Messi 49 in 105, C Ronaldo 55 in 123.
Fat Ronaldo dwarfs both these players as far as international play goes. 62 goals in 98. So did Pele. 77 goals in 91. Pele also scored at the same rate as these guys in club football.
The game favours these players like Messi and Ronaldo scoring massive amounts of goals in club football right now, as the disparity is far worse than it ever has been before in leagues like La Liga, Bundesliga, and Serie A. There's some half-decent competition at the top, but the parity in the lower parts of these leagues is absolutely atrocious, which is also shown by all the records clubs are breaking.
Messi and C. Ronaldo are the best players of their generation and two of the best players of all time (Messi over C. Ronaldo). But trying to claim they are better than the best players of previous generations is rather pointless and silly, and doesn't at all take into account differences in the game.