I'm in the same line of thoughts with you even though I cannot also rule out the fact that the big clubs are there to make their efforts too and they are also trained to take the trophy home. Nevertheless, narrowing down the predictions to only the big English or La Liga clubs is not just enough because if we were to follow the same line of thoughts, we would have written off clubs Like Dortmund which actually got to the final position against Madrid in the last season. So, Champions league should be bigger than those thoughts.
Over the past 20 years, not a single Champions League title has gone to a small or even medium-sized club. Only the top teams took part in the division: only 9 clubs received 20 titles. If we take away Real, the situation would look more diversified, but still, the last time a small club took the title was 21 years ago and it was Porto. Therefore, if you look at the situation objectively, in each season it is easy to assume that one of the top will take the title, and given the fact that some clubs are in crisis, for example Barcelona, the choice becomes even smaller.
I do not know what you mean by top teams because the top teams in each of the leagues keeps changing with just few teams like Real Madrid, Bayern Munic, Barcelona and PSG being regularly at top four. Before, Man Utd and Chelsea were top teams and champions league regulars and even winners of the same league but you will agree with me that we are seeing something different lately. Next season champions league will see some of the supposed top teams absent in the tournament, in this case it becomes an incomplete statement to conclude that champions league is only for the top teams because defining what a top team should be is something very difficult to do.