The fact is that it is strange, because it is a problem pretty evident, since it prevents using CMS to upload files. The solution provided is easy. It has been a long time since the solution was found out.
Beginners like me can go crazy at first.
According to the documentation of the bugs area, this bug has been fixed in some SilverStripe version.
So I do not understand that has not been fixed in SilverStripe 2.4.6.
Thing is it clearly doesn't affect all users - I think it relates to having open base dir set or not for the enviroment. If it totally blocked upload of files I imagine it would have been fixed.
I feel your frustration as a "beginner" silverstripe is a developers CMS, it's not all point and click - it is normally code and build - I guess this is why it is sometime rough around the edges and fixes are often code...
*checkboxes cannot be added to required fields
*save button missing label*
*images being reduced in quality
*(and the file upload thing)
above is my list of "why weren't these included" now it's all on github it is easier than ever to contribute to the code to fix these things - but the fixes have to meet all the criteria.