Ah, you mean _free_ software. Why not be more specific and say that in the first place?
b) the comment you originally reply to didn't even claim anything about licenses "requiring" links to the source, just that doing so is one quite clear way of attributing.
The difference between Open Source and Free software (incidentally, I am in favour of the latter, but this is irrelevant) has to do with ethos and values, not copyleft.
From https://www.gnu.org/philosophy/free-open-overlap.en.html:
"Among all programs that are open source, only a minuscule fraction are not free."
From https://www.gnu.org/philosophy/open-source-misses-the-point....:
"The two now describe almost the same category of software, but they stand for views based on fundamentally different values. For the free software movement, free software is an ethical imperative, essential respect for the users' freedom. By contrast, the philosophy of open source considers issues in terms of how to make software “better”—in a practical sense only. It says that nonfree software is an inferior solution to the practical problem at hand."
You quoted 2 phrases, which are not wrong, but which do not argue against what I wrote before. Here are more quotes from the same pages:
"Second, when a program's source code carries a weak license, one without copyleft, its executables can carry additional nonfree conditions. Microsoft does this with Visual Studio, for example."
It should be quite clear, that, when I can copy a program and modify it and then release under a different license, I can circumvent user freedoms easily. Do you have any counter point to this? What exactly are you trying to tell me?
> ChessBase could easily comply with any open source license by linking the full source code,
"any open source", which is unspecific and gives people the wrong picture, as in MIT, BSD.
"linking the full source code" - how much clearer does the reference to link source code need to be?