Today we can hear many hit and run qso on HF. The purpose of the hit and run qso is to get as many as possible contacts, especially on contesting. Many old folks do not like hit and run qso, they dont hunt for dx station nor partcipating on contest. I read a post from qrq cw operator, ja1nut regarding hit and run qso here http://nuttycellist-unknown.blogspot.com/2013/01/hit-and-run-operators.html
Yes, he was right about the memory keyer. Some people can afford to own high end keyer which can be connected with computer and a paddle on the same time but some dont. That is why their qso is like hit and run qso. One can also type on the enter send mode or non enter send mode, for my own opinion i found that ragchewing is better on the paddle rather than the keyboard.
Passing a turn using BK is not wrong, as a good practice one might send full callsign and other stations callsign. If we hear big dxpedition team who activating rare area, they might use very little transmission message. Their target is to get many contacts as possible, they dont entertain any ragchewer except whom they think is important to reply.
The fact is, listening to this kind of qso wont sharpen our receiving skill. Some people will agree, but some wont. fabian dj1yfk build his own app to wake him up in the morning and transmitting news and emails on cw. Sounds interesting right? He also build an app to translate a pdf file to cw audio. That is how he develop his listening skill.
back to the topic, Not all operator will answer to hit and run operators, but many operators will answer to them. Dont worry about hit and run qso, they will understand. If they have anything to ask, they will send you and email. Old folks will always be a good listener, they will come to your cq call if they want to.