That is indeed an interesting question which is probably relevant for quite a lot of users, so I'm happy to give you my perspective on that:
Unless the situation with your past employers was rather puzzling based on your CV (e.g. odd naming of roles that would suggest otherwise), in closed questioning, you can almost always expect that the interviewer wants to know your reasoning/ the “Why?” of your actions and thoughts. It is still odd that the interviewer didn't ask about your reasoning after your rather brief answer, but I cannot assess the situation from the outside.
Without knowing more details about your situation (e.g. how many employers that you hopped around are we talking? how related were those companies and roles you had?), I would advise you to display such times of seeming discontinuity (as this might be the real reason why interviewers ask such rather obvious questions) rather as a search for professional and personal development. In best case, there is a common theme to your past employers and roles where you can show what you learned from each of them and why hopping around employers was a very conscious decision. Still, I would advise you to clearly state that you would now want to bring in your experience over a long time at the new employer (otherwise, interviewers might fear you would exit again after a brief time).
In case you want a more detailed discussion on what is the best way to answer such behavioral questions, please feel free to to contact me directly.
I hope this helps,