@Arthur Dent As @George Hofmeister has already pointed out, downloading of file types not compatible with the TV operating system will be blocked, as any attempted use of such files would NOT work, and produce confusing error messages for the user. Any operating system for ANY device (TV, router, Set-top-box etc.) would HAVE to protect itself from abuse, otherwise it could be rendered inoperative.
I think you might be trying to compare WebOS, and a smart TV with PC-like attributes, but it is like chalk and cheese comparisons. In any event, Apple devices are VERY restrictive of what can/cannot be installed, as THAT OS is a closed system.