From the v5 Companion:

...many Tzimisce regard the Embrace itself as an act of ownership, and have decidedly traditional relationships with their childer, whom they may even regard as property in extreme cases.

Now if we're talking Old Clan Tzimisce, I interpret this as a legacy of feudalism. The Tzimisce King embraces their chosen Dukes, Earls, Generals, etc. The key here is utility and, likely, some sort of understanding of power and how it is hoarded. These will typically either be childre who can directly contribute to them through the embrace, or they're someone who earned the right to be embraced through demonstrated servitude to their Sire. This, of course, inevitably leads to more Tzimisce "kings" and the ensuing wars we see from v20 lore.

As for younger Tzimisce, I'd take that quote and make it a little more broad. Sure, they're going to sire childre who will contribute to their own holdings, but those holdings aren't just 'big spooky castle in remote part of transylvania'. Instead of embracing purely for royalty and service, they may embrace simply because they want to test their charge with it, or because they find that charge particularly interesting in some way worthy of the embrace (including, but not limited to just keeping that childre locked in a basement to be fleshcrafted and experimented on for the next couple decades)

And of course, you have some who may embrace purely for political, clan agnostic reasons. Someone needs to collect the taxes/enforce the traditions/continue some great work, etc. I think that this may be the case for most young Tzimisce, but only because there's not much material on them outside of their former Sabbat dealings.