Why not banks combine credit cards?

I dont understand why do banks not combine the cards for people having multiple LTF cards? For instance I have HDFC tata neu infinity, swiggy and regalia gold all as LTF and shared limits. Why cant they just combine it for me to have a single card with all the benefits in one?

I know there is a technical challenge there but apart from that what are some other concerns that you can think of?

Edit: To be more clear all I mean is to have a wrapper card that has underlying 3 cards. They may very well have separate limits, milestones, fees (if any)