It should be like that in a team, but there are some players who do make a big contribution and their contribution cannot be replaced, such as Kane in Bayern's front line now, even though there are reserve players to replace him, when Kane is absent, the team will experience a little difficulty and that also applies to almost all teams where there will definitely be mainstay players in a team.
Players who can always be relied on will not always be on the field without getting injured and that is why each team does not only rely on 1 player who contributes the most in the front line because if they do not have a reserve player who has almost the same strength, the club will experience a decline, especially since we also do not know what bad things will happen in the future, sometimes there are players who suffer serious injuries so they are forced to be absent for a full season, therefore, to avoid something that is not desired, the coach must be able to anticipate this.
What is happening to munchen at the moment should be an example and learning for other teams, where losing a mainstay player will have a very negative impact on the team's performance especially if they are very dependent on that player, losing kane has had a negative impact on munchen's current goal productivity and kompany should realise that depending on one player will only make them not optimal to be a champion candidate, having good squad depth is very important in modern football, because injuries and card penalties are an inevitable part of the game, so teams that only rely on one star player are at great risk if that player has to be absent.
Every team actually has more than 1 striker in their squad, but often the coach does not want to rotate players if there is one of the strikers who is consistent and in good form, so when he is injured or absent then other players will be difficult and not optimal to replace the main striker,because of the lack of playing minutes and experience so far.