Actually it was also how every version of Windows prior to 10 did it as well. At least, that's the most obvious interpretation.
I suppose it is possible that MS first trawl your system for exactly what you have installed, its servers then compute a minimal patch file (as supported by Windows installer for nigh-on 20 years) and then builds you a custom unified download. Possible, but insanely complex, compute-intensive (on the server side) and bug-prone (since the whole scheme is broken by just one unaccounted for patch in the whole history of Windows).
But it is vastly more plausible to assume that they've recognised what a dumb idea it was to ship each month's updates in a single package, have reverted to the old system of issuing separate patches for each installed component, but have not reverted to the old system of letting you tick or not tick each one prior to acceptance.