Entry level products (AVR's under $1000. +/-) do not rebuild signal level.
They can and do de-serialize the audio portion and overlay OSD but this does not mean that they improve signal level (it is all about cost).
Our restorer cost (retail) about the same as an entry level AVR (and we are not making a killing).
As you increase the retail price of an AVR you will (or should) get better video processing (mostly analog to digital) and better signal path design/build (which will reduce loss).
Proper HDMI board design/build is the single most expensive cost item in the build of an AVR, that being the case mfgr's do as little as possible to meet market/price requirements.

I received a video today taken by a dealer where he pulled the case off of an AVR and found that that HDMI portion of the AVR (in the top right front)was connected to the rear panel jack by an actual HDMI cable w/ right angle adapters (which can add to the loss) instead of a proper trace eq'd & balanced signal path (I will only say that it was NOT a Denon product).
This in my opinion is a cheap/shoddy way to do this.