The Nostalgia - PlayStation fans wanted to feel the nostalgia of gaming. Since PSNow has been announced, the PS3 and PS2 catalogues have a limited number of games and Sony adds more of them every month, but not my favorite games. I agree with the fanbase that PSNow should have every single game across the PlayStation family, but minus the PSP and PSVita games for the separate accessory and have the catalogue of PS1 games so we can feel the nostalgia of older games.
Favorite Classics - I enjoy the types of games that have became a refresher course of nature. Mainly, my favorite PS1 and PS2 games. They are the best to enjoy. For example, take the Crash Bandicoot games for example, but most notably, The Wrath of Cortex. It's my number one favorite that I enjoyed playing since Bomberman Hero became my favorite N64 game and Naughty Dog isn't responsible of that because it's also for the original Xbox and GameCube. Fortunately, Activision wanted us to expect more of their Crash and Spyro remasters this year, so this one and Enter the Dragonfly might be next in line to be remastered, but since the PS4's life cycle is slowly approaching the end as we move on to the PS5 coming this year, they might be ported to the newest console.
Gaming Marathons - Now this is the most important reason why the PS5 needs full backwards compatibility. If you know about movie marathons, then you'll know about gaming marathons. Gaming marathons associate with playing and streaming the series in order and vice versa through generations. It's like a Let's Play series, but better. For example, let's say people wanted to stream and do a Gran Turismo marathon. They start from the very first Gran Turismo for the PS1 all the way to Gran Turismo 7 for the PS5 and vice versa. I don't know what series I should play in order.
Defunct Video Game Companies - I'm fond of missing video game companies that are defunct and bought out by their parent companies, but not often. Parent video game companies like Infinity Ward bought out Neversoft, Nordic Games bought out THQ, Inc. before they become THQ Nordic, etc. were often fates to the defunct companies.
Those are the above reasons why the PS5 should have full backwards compatibility. I signed the petition for Sony to take this into extreme consideration. As it stands now, over 1,675 people have signed it, so less than 825 people must sign it. And Sony, if you're reading this, full backwards compatibility or riot. Signing out.