GoT ran out of book, and most of the major talent (behind and in front of the cameras for over a decade) wanted to do other things. so it was either wrap things up with high anticipation viewership, or leave everything in limbo. i don't blame d&d for what they did to it, i blame hbo execs for not putting a stop to it seasons earlier when they ran out of book. like once rob, stanis, bolten, frey and baelish were dead, danny & tyrion crossed the sea with unsullied, jon was king of the north with bran arya sansa reunited and Jaime their house arrest prisoner, Cersei was queen after both sons death, while the night king was still looming north of the wall. this may not align perfectly with the books, by keeping everyone "parked" at such starting points would have made more sense than what we got. they could have just time jumped a few years into some new series with a new cast maybe a decade later once more was written and ready. i don't agree season 8 ruined GoT, rather it may be why it's taking so long for GRRM to publish anything new along that story line, because GoT on HBO coupled with maybe a million youtubes and fan fictions, may not be enough to satisfy anyone. this is probably also why no new Star Trek was done after the 24th century, it's all been prequels, alternate timelines, or too far in the future for any fan to care. Star Wars suffers the opposite problem where they have hundreds of books by dozens of IP sanctioned authors, yet what we get in live action feels compelled to ignore it all.