Gutenberg spell checking via a browser is 1/2 what spell checking should be. The checker should be able to learn words. I’ve spent years training my WordPress spell checker scientific, technical, and mathematical words. Now Chrome wants to label them as misspelled.
Lack of grammar checking is a problem for me too. The classic editor allows rudimentary checking of grammar. It is a god send. I write passive sentences that I want to root out. I type a word twice in a row. Etc. I really benefit from a grammar checker.
I can write in MS Word and transfer the whole thing over, but that is multiple extra steps. There is no “preview” available for how it will look on the page. So, I write and paste, preview, and then write and paste again and check the preview again. Etc. Forget about heavy editing of a post–it must be extracted (headings and all) and returned to MS Word. Also, MS Word is for limited use on my system where I have a subscription that is slow. It is so slow that I really use it only for reading documents that I receive now and then.
Please restore spell checking and grammar checking. If you can do that, I’ll take Gutenberg more seriously.