In the videos and posts examining the ASUS Equalizer cable that I've seen recently, people have made a fundamental mistake by considering only the current through the wires/pins instead of the thermal dissipation. We care more about thermal dissipation than current because dissipation is what causes connectors to melt. Looking at the ASUS cable, it's obvious that it reduces the risk of a fire, as I will explain below.

Let's take a look at some realistic numbers for a bad scenario that could result in a fire with a regular cable. At both ends of the connector let's assume we've done a really bad job plugging it in and mangled 3 ground and 3 power pins on one side of the connector but we have a good connection on the other side, say 15 mohm and 1 mohm for the bad and good pins respectively. On each end of the connector we've mangled opposite sides so each bad pin connects to a good pin on the opposite end of the cable. It's realistic that half your contacts are significantly worse than the others if you consider people shoving a panel against a cable and folding it over. We also just have a pretty normal 45cm cable for 6 mohm resistance in each wire. Something very important to note here is that every pin-wire-pin connection will be identical.

Now let's analyse the dissipation, it's quite simple because every pin-wire-pin combination is 1mΩ-6mΩ-15mΩ. At a total 50A load, this gives us 0.07W-0.4W-1W. Put 6 of those on the end of the cable and we've got 6W in the half of connector (and 6.4W total), which is probably enough to start melting it, especially given that the GPU will be hot from drawing 50A so we can't dissipate much into the PCB. Or maybe it's not and we instead need 10mΩ and 100mΩ instead of 1mΩ and 15mΩ, but all the same logic and results still apply for those numbers.

Note again that our current balance would be perfect here but our dissipation is not.

Here is a link to a simulation of what this would look like for just the 12V side of the connector in case my explanation is not clear.

Now let's consider what happens when we add ASUS's bridge. We effectively split our network into two series networks, so let's look at each side separately:

The first has the wire and the PSU side connector, resulting in six lots of 15mΩ-6mΩ and 6 lots of 1mΩ-6mΩ. I'm not going to write out all the maths here, but that gives us 0.26W-0.1W and 0.15W-1W, so not nearly as much dissipation in the connector (2.5 W total and not concentrated too much on one side) and 1W in each wire for half the wires, over a 45cm wire that's nothing.

Note here that the current balance is now really bad, but the resulting dissipation is lower, both in total and in the highest dissipation pins.

The second resistor network consists of the GPU connector pins in parallel: 3 lots of 1mΩ and 3 lots of 15mΩ, or 0.24W and 0.01W. This gives us only 1.5W in the GPU connector. It is all concentrated on one side, but it's 4 times less than the 6 W we have on one side without the bridge.

You might think, "But wait, that's 15A through some of the pins, isn't that really bad?". The answer is no because the low resistance results in very little thermal dissipation. If the resistance increases, less current flows through that pin because the current distributes to the other pins, keeping thermal dissipation low.

As you can see, the bridge is a very good solution here despite worsening the current balance. Current balance is ultimately just a symptom, one that is easily measured, but it is not what we actually care about for preventing a fire.