Literally Bungie; "Hey everyone hates end game content because it takes ten hours and gives half the amount of loot as a 5 minute activity. How can we fix this... Oh I know, let's make everything else slightly harder to mildly annoy all veteran players, and punish new players, because some crappy YouTuber who doesn't work a real job said so... Oh btw we're going to talk about accessibility for 5 months, but then reset your power level so that everything you did before doesn't matter".
First off they boosted your power level… this is so all players start at the same level. Your previous level boosting was relevant to the previous seasons and DLC, secondly the game is not hard… having soloed the campaign on legend, you simply need to plan your tactics… its a shooter game, that concept should be expected. If you want something super easy, perhaps play a different game.