That’s why you use a teapot and warm the pot. The ritual is fun, and you can get more than one mug out of it too.
At least the OP isn’t microwaving the teabag in the mug, that would be truly barbaric.
I always heard the water can get superheated and explode all over you.
At 110 volts, our electric kettles aren’t great. I still have two because we don’t have a microwave. 
Sounds nice, but real barbarians would drink mead.
The Lyme Bay stuff is good. Drinking horns optional.
Or a nice Merlot . . . we’re barbarians not savages!
Stranger
Vodka Redbull has all the same effects without causing insanity. The wonders of modern technology. 
If you’ve ever seen a roomful of 20-somethings heavily into drinking booze and Redbull simultaneously, you’d know the insanity thing is quite real with modern tech too.
'Zactly. This is how I make tea. Get the water and mug up to near boiling, remove from microwave, steep the tea, and drink.
I grant that if I drank tea by the potful then the “proper” British method with electric kettle and stoneware teapot might be superior as to convenience if not as to taste. But for my one cup per week-ish habit, the microwave makes very hot water just great, and steeping in the cup works well too.
I used to heat water in the microwave. A couple scary water bursts scared me enough to stop.
Now I use the same method as my grandmother. They’re about $7 and last a long time.
Like the OP, I put the teabag in after heating. I set my phone timer to 3 minutes.
I just told my husband about this discussion, and he threatened to make my tea by putting the tea bag in after the water to see if I can tell. 
But he rarely makes my tea, so I don’t know how much danger I’m in…
That’s unfair. We’re all boring gainfully employed 30-40 somethings now.
My advice: Hide the henbane first.
When living in the dorm my contraband microwave never caused any problems. My neighbor with one of those electric coils that go in a cup accidentally started a fire with it. I think those were prohibited, too.
There’s nothing wrong with it. Negative reactions are pure snobbery.
It just doesn’t taste right to me. I don’t know why. I can tell if someone gives me a mug of tea made that way.
Microwaving water destroys the homeopathic memory of it’s past in the ground. The ground is where tea plants are grown so the tea and the water normally have a common homeopathic memory. Without that the brewed beverage can never be right.
There is a real and significant difference between water that has been held at a rolling boil for awhile (a minute or several) versus water that has merely been raised from cool or tepid to e.g. 90C / 195F then promptly used.
All those bubbles in actively boiling water represent at least some dissolved gasses and impurities coming out. Water that is merely warmed to near-boiling then removed from the heat still has all those dissolved gasses in it.
I personally don’t think that either one is “better” than the other. But if somebody is used to method A, then method B will taste “off” to you. And vice versa. For legitimate chemical reasons. And “taste” (like smell) is really just a detection system for various chemicals.
Use the method that achieves the result you prefer.
So, first, the obvious, the XKCD was going for the funnies.
But it’s not any different than our countless threads on the right way to BBQ, the right toppings for pizza, or any other personal, regional, or national obsessions with food. I mean, I grew up with sun tea in southern NM, which is yet another kettle of fish. And we’re all leaving out the fact that many tea purists would happily lynch any of us who are using TEA BAGS in the first place!
For the record, I’m an American, and make my hot water for tea with an electric kettle, because my mugs, despite claims, are imperfectly safe in the microwave. Not because of any chemical leaching, but because I can and have burned my hands on the handles!
But having a local teahouse that does the full boiling kettle, heating the cups, heating the pots, first rinse of the tea leaves etc, along with a detailed discussion on the health benefits of each of the blends, the Brits are going to have to wait their turn for disgust after the various Asian tea drinking societies.
All in good fun of course.
I don’t personally check the temperature of water coming from either the microwave OR a kettle on the stove. I doubt it’s ever 97 degrees, consistent or not.
There are, I gather, people who still argue that microwave heating is somehow less wholesome . Someone I knew, 20 years back, declined to have a microwave because of concerns over its effect on the food. Not just “not browned” or whatever, but some vague “does something bad to it”.
Aside from that (which I obviously disagree with), the only dangers with making tea from microwaved water are:
If it isn’t Lapsang Souchong you’re doing it wrong. All else is undrinkable swill. So there. Neener neener. 