The bike industry faces a slightly unique issue, which is the amount of the ‘Value’ of any product sold which is overtly branded as someone else’s product. If you think about it, can you name a single industry where the thing you’re buying is so heavily branded as someone else? While it might be true that any given industry (cars and electronics as the best example) rely heavily on the products of 3rd party suppliers, by the time it reaches the consumer, the bulk of those are well hidden away. Sure your car probably has Air Con designed by a company that supplies 20 different car manufacturers, but you’d never know that. The bike industry has rightly or wrongly built up around the concept that what you buy is an amalgamation of many suppliers, all right there and in your face what with the branding and all.
The problem this creates is that in order to deliver new product, you have to overtly deliver your suppliers new product too. SRAM/Shimano etc. don’t actually run particularly rapid cycles, but when you take them all together, the cycles become quite quick. I can guarantee if the product was own brand 99% throughout (like Ford sticking its logo on someone else’s switchgear), the cycles would be alot slower. That means that manufacturers have become attuned to annual cycles in order to emphasise the ‘newness’. One way to do that is through specific annual cycles. Its also true I think (Not really my area of expertise) that the market used to be dominated by a sell at a premium when its new, then discount heavily model, but more recently supply has been more measured to ensure that you run down the stock at a more appropriate rate than before, which leads to supply issues at the late end of the cycle.
Also worth considering is the seasonality – we’re (and likewise I am sure everyone else) already start to feel the end of the season at around this time of year, so while the timing might be annoying, its also the time of year where changing out models will be less impact than earlier, but likewise gets ahead in the arms race of next years bikes.
Not saying I think this all is a workable model (We don’t do model years, and have been selling ‘2018’ bikes for months now), just that its an understandable side effect of the product that you’re buying,