Why doesnt ranked end with highest earned rank vs wherever youre at the last day of season?

Topic question, why wouldn't riot place summoners highest earned rank through the season vs what rank you're in the last day of the season.

Example last season I was gold 3 and the last week I dropped gold 5 0 lp so I decided to just not ranked for a whole week to just earn gold. Wouldn't it be smarter to just let a gold earned player earn gold even if they drop to silver the last day of the season? What are the pros an cons? I'm curious to see what the community thinks/feels of the two choices.

For the record I'm in promotion for gold 1 and if I get platinum so early in the year it seems that I should be rewarded for plat even if I drop back to gold. Otherwise it incentovises people to not play many games especially if closer to end of season. Shouldn't we be rewarded for our best efforts of the year based on our best placement? We also should be expected to want to play more games to get better and have fun. Not less to earn a possibility of a better standing in case of losses?

What do you guys think? What does riot think?