As far as I know nobody complained about rangefinder flare with the M3, M2, M4, or M5. Depending on who you ask, Leica modified the rangefinder either to simplify, cut costs, or brighten things up. Whatever the reason, they took out a condenser lens and people started complaining about flare. They offered a "modification" to put the condenser back and the flare problem was fixed.
Some cameras do seem worse than others. My late M4-2 shouldn't be much different than an M6, but seems to flare far less. The one M6 I owned briefly was was less than satisfactory to me (not necessarily to you), but a friend has one that seems only marginally worse than my M4-2. The flare is very situation dependent. I am almost never bothered by rangefinder flare with my M4-2, but did encounter it regularly in a particular setting last week.
I apologize if you took my comment as an insult. I was saying that perhaps there was something to your post other than BS and have edited my post to make that more clear. Nonetheless, I don't think people are likely to respond well to the implication that there is only one proper way to use a Leica.
This thread was about rangefinder flare, which is clearly not an interest that you have.
I have owned (4) leica M6's and (1) MP. The rangefinder flare is not as much of a problem as people make it out to be. I still have an M6 that flares once in a while, it is not a problem. I will say however that the patch was much more contrasty in the MP.
How do you know that it is not exactly the amount of problem for me as I make it out to be? I thought I got to decide that.
When I got an M4 back from a shutter replacement service, the docket said something like also 'fitted a finder enhancement to reduce flare', think it was a factory suggested modification. It never flared like a M6 either before or after the service, the M2 and M3s never flare like a M6...
An early M4-2 never flared like a/my M6.
My M6 would flare with a light source in top right part of scene just outside 5cm 24x36 frame, but only the rangefinder spot flared, it went 100% white. The M6 had bad zinc rot as well.
Leica did not seem overly concerned about customer satisfaction, but now MPs are nice.
My French is not so good...