Where are the discussions at the start of lesson blocks?
The posts at the start of each lesson blocks are gone. For some of the more difficult topics -- modals, subjunctive, difficult tenses, dates and numbers -- this was a place to get some key information, and -- sometimes -- to get links to other sites to actually learn the grammar. Duo is far from being a stand-alone site yet; not having this additional information from the community is very problematic. (Also, on Linux Chrome anyway, the carriage return is broken. This should have been three paragraphs.)
Upvote. They were extremely useful in the last lessons. Without them, those are very frustrating.
(Also, Carriage Return is broken sometimes on Firefox in Windows as well. Not always - no idea why, I suspect it has to do with mouse focus. Since it played a sentence once when I pressed enter, I suspect it gets stuck on some Flash element that isn't even on the current screen (or shouldn't be).)
I think the most people who didn't read those discussions are the people who do only a few lessons and give up. The users who really learn a language from Duolingo is those people who do all lessons and read those discussions at the start of the lessons. This is the difference between quantity and quality. What does Duolingo cares about most? Quantity or quality? People who really will learn a language or people who at most will learn some greetings, some food and animal names and so on, and will never use the language for talking, reading etc., and will never be able to translate a text?
I agree with you, for the harder subjects, I would have given up on Duolingo had I not discovered excellent tutorials written by members of the community. It is a total shame to get rid of them for the sake of 'gamififying' (US verbification, ugh).
And it's not very easy to find them by searching, because they weren't often given names like Everything you need to know about Clitics. Instead excellent information might be buried under Suicidal owls, read this!—accurate titles weren't necessary since they were always upvoted to the top of the skill discussion page.