Yes, I agree with that Regionalism is biggest problem in us.
It is existing in new generation ALSO.
I may be wrong, but I observed this problem MORE with the people who belongs to Kumaon region. In garhwal all people says we are Garhwali. But anybody belongs to Kumaon region they says we are Pahadi. I saw, ki, any Garhwali easily wishes to marry with Kumaoni but Kumaoni will think about it many times. I may wrong, but it is my personal experience.
Actually it is a "Garhwal" word who unites us ALL and common in "Pauri Garhwal", Chamoli Garhwal", Tehri Garhwal" and "Kumaon Garhwal". In Himachal people belongs to different places like upper side Kumarsen, Kotgarh, Kaathgarh etc... and also belongs to Una, Mandi, Dharampur etc.. even their costumes and customs are also different but they always tell you k they belongs to HIMACHAL. But we people see each other at a difference.
We devide ourselves, e.g. inn transportation 'GMOU' bus service or 'KMOU' bus service. yahin par difference. Atleast pahle toh yahi chalta tha aajkal i can't say. I hear it from old folk songs and 'ek-dusrey ke baaton se' I went Garhwal 1/2 time, but lots of value for our 'Region'.