I'm not sure they innovated much. Other apps like Babbel are older and had the same features, if not more and better. Duolingo rode the 'free' and 'hip startup' publicity wave and had an interesting idea that they'd use the users to crowdsource translations. But that didn't pan out - everything afterwards seems to have been just scaling with no innovation whatsoever.
Can only agree. Duolingo gives some basic vocabulary but after that basically is useless, especially as the way it teaches grammar forms (and on the mobile app barely any explicit rules) is 100% useless. Native speakers looking at example sentences in the target language are often shocked at the nonsense that is provided.
But worst for me is that it wastes time. The unnecessarily ineffective repetitions, all the features and ads intended to upsell 'Pro', etc. There are dozens of other apps that do it better for free (e.g. good old Anki, or newcomers like Clozemaster) and when on a desktop a whole wealth of professional learning resources are available, both old ones that are now public domain, the world of wikis and collaborative learning and flashcards, and no-profit materials. For instance lots of organizations fund free courses, e.g. the EU funded a bunch of sites for learning languages, like https://deutsch.info, and national broadcasters like RF1 (French), DW (German) provide great professional and current materials. Podcasts and youtubers teach any language imaginable, etc.
Try Duolingo to get a taste, but after a few lessons look for your language online and you'll find much better stuff.
They have a great FAQ explaining that and I agree with their conclusion - all the encryption claims by other providers are nonsense and don't offer real protection.
I had this issue too - all rules were deleted as they switched form regex to something else. I have no idea whether I missed anything and they really could have done an anouncement.
Otherwise have been quite happy and except for a lack of calendar it all works quite well.
In the UK maybe, not most countries. There are some corporate databases that consumers eill mever hear about, but certainly nothing even close to US credit scores.
https://www.bbc.com/news/world-asia-38660860
Although it probably takes a few years for all toilets to be replaced...