Because the whole 2016 roadmap and the whole 2017 roadmap was also about scalability. All they've done so far is throw their hands up and say "it's a really hard problem trust us guys". And nobody has shown any sort of traction on a solution: the developers admitted Lightning Network won't solve scalability concerns.
Some people are getting a little tired of the pony show.
Then people will move to Ethereum and EOS (or whatever competing blockchains get scalability first). With interoperability of blockchains, transactions can be done on alt blockchains that are cheap and fast instead of on the Bitcoin chain.
Some people are getting a little tired of the pony show.