Never seen this style in my life....Never seen this effect...........

Exactly why was it banned?

Was not practical...both at the cabinet to wire them up, or to install a 5-light where a 4-light costs/weighs less. The only places that used these did them in a trial run and retrofitting existing doghouses. A four section R Y flashing Y and G, a three section R Y and Flashing Y/G Bimodal, or an all permissive 3 section R Y Flashing Y is allowed.

What was the point of having two full circle yellow lights versus just one? Also how come the traditional four section R-Y-G-Y/G signals or traditional R-Y-G-Y-G doghouses be used? They seem a lot less complicated and are much easier to understand IMO. That's what's currently installed here. Around here it's go on the green arrow, yield when there's no arrow. Only the R-Y-G arrow signals are easier to understand than that. I wouldn't know what the hell to do if i saw a flashing yellow arrow on a four section signal.

yellow flashing always means yield and flashing red always treat like a stop sign. Also reason to have those setups is sometimes you can't go straight but still can turn left. In Maryland here, we have sometimes have a sign that explains what "flashing red" means right next to the traffic light flashing red. There's a few just near me a few blocks away!

Here when you can't go straight but can go left, the red ball is lit but the green arrow is also lit. The red ball says traffic can't go straight but the green arrow means you can go left. I'll make a diagram...

Yeah it's a normal setup, a common setup....but we have some unusual setups such as U turn light like this

Yeah, here's how Ontario's left turn lights are. Oh and here's our version of the U turn light.