As you go into lower tiers, punishments for corner pokers are both easier to do and greater in impact, it becomes easier for others to retaliate against you, and the loss in potential DPM for ducking or being pressured into cover with a reloaded gun is greater. Look at the ratio of DPM to health between the tiers. It doesn't get any lower than what it is at tier 10, and when you factor in the impact of armor and shell RNG either missing or hitting angled/high-armored spots on top of that, the pace deteriorates. High alpha and high burst tanks also exist in the low tiers. The high alpha ones reload faster than their high tier counterparts, and if you're going to complain about being the target of a burst tank, then you're either fucking up hard to sit where someone can put a whole clip into you or the victim of a risky rush play that you can't defend against because your tank is too slow at moving and reloading because it isn't a low tier. In either case, low tiers will burst down same-tier targets faster than high tier counterparts.
I've got no experience to refute your 3-4 minute number, but if this is something that only happens in cases where arty exists, and nobody seems to want arty to exist, then it follows that people would rather have their long, superheavy corner-humping matches in the high tiers, which doesn't lead to faster gameplay than what is found in the lower tiers.
Seeing as you only grinded up a line that is mean't for hull down corner poking with low dpm its easy to see why you're complaining pointlessly about high tiers. If you like yolo dpm CHAI sniping like you said in your blog; play the tier 10 RU meds. You cannot pretend to have ANY professional opinions when you just padded in a hellcat and T2. You havent even grinded out a tier 10 and picked a terrible starter line. Dont be surprised if people smack you down when you try to talk shit about high tiers.