Lately I've noticed more and more people on the platform doing the "oh no, you go first" thing and selflessly standing by and letting others board the train first. I've even witnessed two or more such chivalrous folks come close to an unchivalrous argument about who should go last. That's when it dawned on me, this is not any kind of selfless behavior, it's the opposite kind! These people are trying to be the last on so they can be first off at their stop, and it's starting to delay the whole boarding process when first they dawdle and squabble about who's to be last, and then they bottleneck the door area making it harder again to get on or off at any stop till theirs. Well, that's more like the Boston I know.
If you need a refresher on how to use the MBTA, I suggest the MBTA Etiquette Handbook, this section in particular:
3. The doors
Do not stand directly next to the doors if possible. This makes it difficult for people to exit/enter the train. If you are standing at the door because the train is too full, get off the train and let people leave. You will be the first one back on and you’ll be able to get a better spot to stand, or maybe even a seat. The train won’t leave without you if you get off for three seconds.