Most teabags I use now don't split (some imported brands you have to be careful with), these are just regular looking ones not the fine mesh ones used by premium brands. I can jam them against the side of the cup to squeeze out liquid before removing the bag and they almost never split.

I'd say these extra strong bags have become common in the last 15 years in the UK. How they are strengthened I'm not sure, but my parents compost most of their food waste and they reckon worms now push teabags to the top of the compost bin, when previously they would just disappear with everything else and never be seen again.