I think you can absolutely love a videogame's story, characters, world, lore, etc. by watching playthroughs.
However, it is ridiculous to say that someone that watched a game had a similar experience to someone who played it. Idk why people are so reductive to this artform to where folks do not consider the MAIN way to engage with a videogame as the utmost level of importance when discussing it.
Videogames are entirely unique from every form of entertainment in that the way you interact with it can VASTLY impact someone's experience. There are just things in games that are only effective if YOU'RE the one making these decisions and doing these things rather than watching someone else do it.