shouldve pinged me with this message, i never knew anyone responded.
first, no, tier 7+ heavies have weakspots, they are almost never invulnerable from the front (either cupolas, weak hulls, or machine gun ports)
second, most tanks that are heavily armored are also pretty slow, or have subpar guns (either dpm, accuracy, or alpha dmg etc), and will very easily be overwhelmed even by 1 or 2 decently mobile tanks in a hilly area (in a city area there is more solid cover and places to wedge any pesky tanks on your ass). the accuracy part is partially true for a few tanks but most guns take at least a little big to reaim even when only moving the turret to track a fast moving light or medium.
lastly, no, tier 8 or 9 fast tanks are still very good in the hands of a skilled player even against bs premium heavies and tds. the bourrasque is one of those op ass premium tanks but it shows that mobility and an above average gun can make a tank a very formidable opponent. the uh tier 9 sheridan thing (cant remember name) is devastating when used properly with its massive gun and good mobility (most of the time it doesnt even need mobility as having a big derp gun is good enough for a lot of tanks). in essence, map design should favour both slow heavily armoured tanks and fast lightly armoured tanks depending on what side the tanks play on, there should never be one specific map that causes one type of tank to outshine another.