nothing wrong with that (if you want to assume that's why they did it). personally I think they wanted to bring down the component cost and this was the way. I doubt they'd have enough duds to sustain a separate product line - eventually they'd have to start purposefully disabling cores on otherwise good chips. we'll never know though...
Well, in the initial order for iPhone 14 Pro models, figure about 50% of the initial 90M units were Pro’s (even more now due to higher demand than anticipated), so did they had TSMC build only 45M chips from wafers? No, because yields are never 100%, far from it. Also, because of using the N5+ node, it was still being sorted out from a production yield standpoint.
Even if TSMC had 90% yield, which would be pretty extraordinary, not all are 100% usable in full spec. This drops the best chips yield even further to say 85%. So TSMC has to build at least 45M/85% = ~53M chips to supply initial order, leaving at least 7-8M chips that don’t meet full spec but something less which could be controlled by laser cutoff or software cutoff of the defective chip area. That’s a lot of usable chips for an application or device which doesn’t need 100% spec - like an Apple TV 4K update, maybe a new iPhone SE Model, maybe another iPad model next year. The ATV wouldn’t sell that many in a year (yet) but a new updated iPhone SE certainly could, that’s why with continued A15 production, there will always be variants available.
And yes, sometimes they even put in perfectly good chips that are constrained or throttled back just to get the product out. (happened in the remanufactured auto parts area - a big Japanese auto company was selling reman alternators at lower prices at their dealers. Demand was so brisk that they couldn’t get enough cores to rebuild. But to give the consumer choice, they decided to keep the reman part (along with the new part) in stock. How? They put new alternators in reman boxes and ate the difference. Consumers had the choice and many times still chose new over reman.)
It’s called usable chips repurposed for sale and use in an applicable device. Intel did it all the time with original Pentium and subsequent Core and iX-yyyy models with all the “steppings” which were slightly different specs of clock frequency, cores, etc. they sold them at different prices for different performance.
[[Yeah I’m thinking iPhone rejects.]]
Maybe so, I prefer to think of it as lesser performance but still quite usable chips within the A15 family. That Apple chooses not to ID them with a different public number but rather just describe them by cores is marketing and avoiding tech speak.
Consider these chips A15 variants.