Well I think this all comes down to people that are non technical having trouble looking at the consequences of their actions.
This is a receiver HDMI board.
That is not even a 4 K board. That does not look a good idea to start drawing power from a board like that.
Next the pre pro I have ordered has three HDMI outputs and therefore someone could potentially draw 750 mw form the HDMI board, which is 150 ma.
I doubt that is a good idea. I would say an HDMI board is much more likely to blow than and HDMI board. They are also only the fraction of the cost of an HDMI board and much more easily replaced.
Finally the specs of these cables are vague. Is that 250 ma peak power or average power. Since it is a processing chip it is highly unlikely the power draw is constant.
So until there are world recognized standards and ways of specifying these cables and HDMI boards and boards, my advice to members asking about any type of active HDMI cable is to ALWAYS use a voltage inserter. That seems to me the most sensible and wisest approach.