Sure, it is all public: All you need to do is browse CF repositories, there is lots of interesting things there that should stop people saying: "CF does nothing", does way more than one thinks and often 1 person in the organisation works for 2 in terms of workload.

Sure, When writing code to develop an application in the traditional world (non blockchain), usually, you have to interact with other services like for example a database. Now, most of the database provider (like mysql, postgres, oracle etc) have made super simple to run a database on your computer or laptop. When developing a dApp on Cardano, or other blockchain, you MUST talk to a blockchain. Cardano has 3 main chains: preview, preprod, mainnet. Developing against REAL blockchain can be slow and problematic: you must fund wallets you want to use, wait for blocks to be produced every 20 seconds etc etc... on top of that, you need to talk to the blockchain, so you need an account on maestro, blockfrost etc.... Even worse, if you're 40k feet on an airplane on a 10h flight, you can't work, coz you got no internet. A DevKit is a "kit" or "toolbox" which give you ALL you need to write a dApp on Cardano w/o being connected to interenet or something. Chain is superfast (1second block for example) and you can fund all teh wallets you want, mint tokens etc, just w/ a snap of the finger. 0 wait time. Blockfrost, ogmios and all this is running already for you, for free etc. As result, writing code is much faster experience, faster feedback etc and should make people happier and less frustrated. Does it help?