First of all: Take a look in the wiki log and you will see that every
day things are updated or added.
That's no excuse for the absence of a compact general documentation or help on all classes, properties and methods. The interfaces don't change so often, or cannot be changed at all for Delphi compatibility.
About the forum vs wiki: There are many experts in the various forums
writing good advices and sometimes lengthy explanations. I wish they
would instead add the hints to the wiki and just post a link in the
forum.
Just *lengthy* explanations are not the base of useful OH.
All contributions should be verified, by people with according knowledge, i.e. the implementors in the first place. These also can add hints on topics which are subject to changes.
Instead of adding to the wiki, notes also could be created by fpdoc and added to the SVN, provided that every user has write access to the documentation folder.
It is true, that the quality of the Delphi help is really good - and
in too many areas better than the lazarus help. But "no usable
documentation" is a bad exaggeration. There are for example more than
1000 wiki pages and the lcl fpdoc contains more than 30.000 notes.
Useful help must be structured, with links from the general keys (identifiers in source code) to all the related information. It must not be scattered across a number of unrelated and unlinked places.
Delphi help is good because it is structured, and every piece has its place in that structure. It has taken CG many years, to find a useful replacement for the old WinHelp, and to move all contents to the new structure. That's not fun, that's hard work. I already have considered to write my own documentation, and to sell it as a service...
Lazarus also could ask CG for a license for the Delphi help, so that most parts can be ported by copy&paste. Then it were up to the implementors, to add the Lazarus specific notes, and finally everybody could add examples and other stuff.
DoDi