Simple way to improve themes documentation

I'm in process of choosing a theme for a new site, and found that some themes do not provide all the basic display functionality that Drupal offers. For example, some themes don't allow left and right blocks (all blocks are placed in only one side, ignoring the settings in administer>blocks). Others don't show secondary links by default, but in administer>themes>configure you are still given the choice to show or hide them.
It took me some time to find out that nothing was wrong with my installation. Because, if you set secondary links to show, check and re-check that you configured them properly, and still they don't show up, the natural conclusion is that you have a bug.
I understand that a theme can have a specific purpose (ex. only a blog) in which secondary links or bars at both sides are absolutely unnecessary, not compromising its usefulness. But, if this is the case, it should be clearly written anywhere (preferably the download page) that some basic Drupal functionality is unavailable. This simple note could save lots of trouble.