@Ascension Sir, what if there is issue (technical or any other issue) with demat itself? One can have multiple reasons for opening more than one Demat account. For example :
1.To maintain separate long term and short term accounts. Be investor as well as trader.
2. To take care of technical disruptions / no-service by a particular broker at critical times.
3. Take advantage of research, analysis, insights, user interface, charts etc provided by different brokers.
However, one should be averse of maintenance charges and time/efforts required to maintain multiple accounts. It is personal choice.
Agreed?