Cities other than delhi, comparable in area, have a comparable number of vehicles, but no smog issue. Bangalore for example now has more vehicles than Delhi. I have not been able to find out conclusive answer as to why, but one of the answers is just the general geography of the region.
The 10/15 year rule is not primarily aimed at reducing pollution, the point is to reduce the number of cars on the road. It's unfair because only poor people who cannot afford to buy new cars will suffer, but it seems to be working. They can't just outright say their motives to our face but this is what it is.
Apparently a good portion of the smog comes from brake and road dust (tyre wear). Most publications seem not to be blaming the stubble burning. I am not sure if this is the reality or if they just want to act woke and not blame the farmers, but the odd/even rule seemed to have worked when it was implemented so it could be true.
Delhi just like most metro cities is overcrowded as h*ck, Delhi is taking the right steps in trying to reduce the number of cars from the road. Where it does lack, is giving the citizens and alternative. Delhi doesn't have enough buses per statistics, and I personally don't know how effective the metro project is. People will curse and swear at expensive cars, taxes, 10/15 years, odd even, but in the end they will buy cars because there is no option. Maybe they will buy a bike, but it will still be a motor vehicle.
If they splurge on public transport and good, safe, maintained cycle paths, with robust campaigns that will encourage people to use these. And simultaneously make it a little more harder to own cars (very phased manner) it will eventually probably work out. It's best to have extensive women-only public transport because women might understandably not want to use a cycles. It's not like I want them to outright ban car ownership but if people just stopped taking cars to daily commutes and take out vehicles for just the weekends, even that is going to be a big help. It needs more effort than a half hearted effort though. It might seem impossible, but it's really not. I'm thinking it's just red tape. They built an automobile-dependent city and now want to reduce the number of cars, maybe if they started to slowly convert it to a cycle centric city it would help. Dutch people are doing really well with their bikes arent they?
(I had written out a long essay about Delhi smog, but I don't want to post the entire thing here.)