Why can't FreeBSD compile anything from source code?
 

It just seems that way anyways.

Things like K3b would not compile.Any Quake2 port I tried would not compile either.

Is FreeBSD married to it's ports or is it possible to compile anything from it's source code?

Or am I trying foolishly to compile linux source codes on a type of system that just don't do that?

I think I just answered my own question.

Perhaps you are doing just that, trying to install source for Linux. Check the programs you are trying to install and check if there is anything about *BSD. If not, the source is probably made for Linux.

To answer your question -- Yes, the BSD's are kind of married to their (ports|pkgsrc). When a package goes into the ports system, the port's build includes patches to make the code work on that particular BSD.

Linux has a lot of stupid little peculiarities that are specific to linux that need to be fixed before they'll work on BSD (or anything else for that matter), and that's what the ports tree is all about.

LOLOL!

Stupid peculiairities.

I like that.

FreeBSD is a real solid OS and I agree that a lot of linux distros have many "stupid peculiairities".

I think that source from many tarballs check if you are using BSD during the configure script.

For example in the streamtuner configure script, there are 37 lines referencing BSD.
Here are the first five such lines:
echo "$as_me:$LINENO: checking for a BSD-compatible install" >&5
echo $ECHO_N "checking for a BSD-compatible install... $ECHO_C" >&6
# (eg FreeBSD returns the mod time of the symlink's containing
# Now try BSD make style include.
_am_result=BSD

The ports are based on source. Go install one and watch her compile. Know that is not what you meant...but true none the less.