This could be seen as an alternate history cliché, or as an outright fault in many timelines: India rarely ever gets covered. Thus, timeline authors also hardly research India. Hence they will simply assume the current state of affairs, a united India. However, united India only came about due to British colonialism. Before it was as disunited as Europe, and it continues to be as culturally diverse as Europe - its provinces could well work as homogenous nation-states, too. The cliché is to always have an united India, no matter how early the PoD, and to always have it a “Here be dragons” territory in regards to the timeline, an area almost completely omitted from the timeline, and to have its cultural differences be simply overlooked.
If India isn't boringly united under the British, it's boringly united under the French, or (rarely) the Mughals. Almost never is India given any thought or changed really in many ways. Britain might go through three civil wars and conquer Denmark in the ATL, but British India just sits, unchanging.
Of course, a member with a strong Indian association - Flocculencio - is the member who gets most irritated about this cliché, particularly when it is tied to pre-modern Japan possessing unrealistic power and dominating the historically culturally Indian East Indies (Indonesia).
Ganesha has noted that, in a variation of a cliché involving South America in timelines, it often seems that “nothing ever happens in India”, in most timelines. Europe could look 100% different after 300 years of ATL, but India will still be boring and nothing important will have happened there.