Ya-Ha!
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Outside of people just hating to read I think it's largely due to how detailed some frames in manga are. It's sometimes hard for inexperienced readers to look at a cluttered frame and make out what is happening fully. With the anime you can see every aspect to a scene while it's animated. As a general manga reader I myself rewatch some scenes I really enjoyed in the manga in anime form once it's available.
Adelaide
easier to binge, its pretty difficult to read a manga while folding laundry
choko_canyon
Watching things is easier than reading them.
Kathy
Because they like it better when they watch it.
LadyMerton
watching is more Passive
reading takes more effort