What makes placement matches different than a promo match or a series match?

Basically that, why should someone in a placement match have to deal with autofill while those in a promo or a series not?

It would be very unethical to give those who have already been playing the game an advantage over those who have just started would it not? Let's say a new player starts, they only place adc or jungle, but yet in their ranked placements when they choose adc and jungle as primary and secondary, they will get an autofill. But then now you have those players that have been playing the game longer than that of the new player who is just placing and they are in a series, this new player does not get an autofill protected in their placement but the vet player will get an autofill protected in their series or promo.

This is a system designed to make new players place lower. This is a system designed to make a skill gap between players, or to keep a skill gap.

Through out my games i noticed while placing on a different account that i played against plat players, but yet i had silver players on my team. There was also an instance where i played against a player that was previously a master yet i was playing with golds on my team. This of course is unrelated to the issue above hand but yet shows the difference that some players played against with this system at the start of this season.

The whole point that i want to make is that, although it has been this way this season, it can be up for grabs to change the system for next season. if you expect players to deal with placements with auto fill with the expectation that you as a provider are getting their average then you are wrong and providing an unethical service by saying "we will autofill protect you from your promo or series because we think you should play your best" you should expect players to play their best in placements as well. and then they should have to deal with the system. that way they know they placed their best at what rank they place. It is unethical to give those who have played the game for a longer time an advantage over those who have played very little and just start their placements.