Liverpool are a good team and they have started the season well. They have dominated everywhere from the English Premier League to the Champions League but the problem is the lack of substitute players in their squad. Liverpool will be in big trouble if for some reason Mohamed Salah or any other key eleven player gets injured. If they lose to other teams after performing so well just because they don't have support players then it will be a matter of regret for them.
Liverpool are not just a good team, they are a very strong team. The problem you identified with the Liverpool team may not be there now. Moreover, you are wrong somewhere because Liverpool has some other important players apart from Md Salha. As you may know, Mac Allister is one of the best players and he is currently performing consistently in every match for Liverpool team. So if ever Md Salha gets injured then maybe Mac Allister can fill his place properly.
I would say it's a bit true, I am not denying that they have other good players, but none of them are as good as Salah, so it's a big deal to have him. In the end, they are not going to really end up with much issues when they are dealing with both sides at the top, they will have a chance to lose a few games and still win the whole thing, and that's what matters.
For example, Liverpool has 2 more games at UCL, if they lose both, they are still in top 8 and they won't really face any issues at all, simple as that. Or they are at premier league, have missing games but still leading, meaning if they lose those games, they would still be the leader. So having that kind of advantage definitely helps everyone on the team a lot, emotionally, mentally and even physically.