What you just described would be even worse as it would be asynchronous, making all the points moving, adding more variation.
http://mathworld.wolfram.com/Circle-CircleIntersection.html
This is what you could manage with two intersecting circles with known radii
We don’t have known radii and Spy doesn’t even check for your Combat Log range. Spy User A could be running at 50 yards whereas Spy User B could be running at 200 yards. Spy makes no check of this, nor does it set the Combat Log itself. And as a reminder: the detection could be anywhere within the range of the Combat Log.
You can only get coordinates of three entities: yourself, your party members, and your raid members. To calculate distances between players, such as range checks for AoE mechanics in PvE, the addon has to pull both players’ coordinates, adjust for hitbox, and calculate the distance between two points formula.
To get coordinates of an enemy player using the Combat Log you’d have to control for:
- Combat Log range
- Only calculate synchronous pings
- Hardcode the overlap area equation based on how many synchronous pings are received
- Approximate the location within the overlap area, again hard coding per ping count
- Place pin
It isn’t just flipping a switch. Area overlap equations aren’t trivial and I haven’t the foggiest how quickly or rapidly LUA can run such equations, or if LUA can even handle trigonometric functions with any accuracy.
Which has nothing to do with the addon because, as you said, people can just report their own positions and say “Rogue near me” and if a bunch of people go zooming around on mounts, they can likely find the Rogue if they come soon enough. As far as numbers are concerned, that’s not exactly some grand secret hidden from non-addon users. Seeing your Combat Log scroll faster than you can read it with spam of the same message, but different names, because someone applied raid buffs to several groups, should be a decent tip off that there are a lot of enemies nearby. That or the spam in chat from some poor lvl23 that got steamrolled.
As are all the other addons people use that had their origins in Vanilla WoW.