I'll argue more with the special merits of carriers subsidies.
Last time I checked with t-mobile uk, it is much cheper to buy the phone separately with a sim only plan than to take a subsidized phone with a plan.
Like, for the same phone and the same plan features, at the end of the 24 month of the contract, the sim only option was 200£ cheaper (plus, the contract is one month only so you can change anytime).

In France there's no correct sim only plans, and I can't say for the rest of the world, but here (uk) carriers subsidies are nothing but a pretty expensive consumer credit with free vendor lock-in.