the issue with an AK and 100 meters isnt about the bullet having the ballistic ability to kill/injure past that distance.. its about the weapons inherent accuracy (or lack of it)..
neither the AK or the 7.62x39 were designed for shooting at long range (or even intermediate range by comparison with most modern assault and battle rifles).. most "good" AK's Ive seen/used are 3-5 MOA guns.. 5 MOA at 100 meters = a 5" group if you do absolutely everything perfectly.. add in the challenges provided by imperfect firing position, weather conditions, elevation, relief, moving targets, the shooter being on the move, stress of combat, etc..etc.. and youre likely looking at 10" groups on a good day for a well trained and capable shooter.. the average run of the mill guy would be challenged to keep the group to 2 feet or less.. (as I have seen countless times on civilian, police, and military ranges)..
stretch that out to 150 meters and you can increase those numbers by well more than 50% (accuracy problems associated with the round will start to come into play and impact results... in addition to the accuracy issues the rifle itself brings)..... which is substantially wider than your average human target..
engaging targets at 200 meters.. is a complete waste of time and ammo for all but the best shooters, pulling the trigger under the most optimum of conditions.... at best you are just keeping heads down at that distance... and getting lucky if you are hitting what you are aiming at...
AK's with precision modifications, etc.. are another story.. I have seen a couple of souped up AK's capable of holding 2 MOA out to 100 yards.. which frankly is remarkable in my opinion for that weapon system..
As someone that has been downrange of a variety of rifles, to include AK's.. I would agree with you.. no one should want to be on the receiving end of one at any distance.. but.. if the shooter is much more than a hundred yards out.. he is most likely in a position of serious disadvantage if I have something better suited for longer range engagements.. there are far better intermediate range options.. and just about anything is better at ranges longer than intermediate..
AK's have been used by more people than any other weapon system for a variety of reasons.. the single most important of which is they are CHEAP on the military market.. they have been sold by the millions at prices far lower than the M16/M4 family of weapons, or any offerings from FN, HK, etc.. to armies all over the globe.. they are also super easy to maintain.. it doesnt take a whole lot of training to get a soldier up to speed with one.. they take a lot of abuse and keep on working.. they dont require a ton of maintenance.. etc..
Im not sure about WASR's and canted barrels only... Ive seen them come from Century with really poor welds.. loose gas blocks.. and a number of other problems.. canted sights were pretty big problem them for a while and a very common complaint among purchasers..
You are correct about the VZ58 being different in function to AK's and all of the variants being made over the years.. the point made about the Czech gun should have been made with more clarity.. weapons coming from the CZ plant(s) have a history of high quality.. all former eastern bloc weapons are not created equally.. a better example would have been to use a Yugo or Polish gun vs a WASR... I would also agree that the Yugo guns are among the best of breed..
I would argue that the online reputation that the WASR has obtained is legitimate.. if you get one that is "good" out of the box.. great.. but.. too many people did/do not... if you want a plinking/fun gun.. it might be a good purchase (cheaper than other options, etc..).. but.. if you want a serious gun, for serious use.. there are far better AK options for only marginally more money..