There's nearly always a certain slickness and comfort with the ball in Spanish DM's, but obviously greater dividing lines come about when we add all factors that make a good or great DM: positional awareness; decision making; confidence under pressure; instinct (where many get accused of hiding, when in actuality, it's taking them that bit too long to process what's going on and what they should be doing at that precise moment.) and so on and so forth. But by and large, you watch them and the technical acumen is so intrinsic, you don't really give it a second thought unless they are exceptionally good with the ball, you also know every one of them with NT aspirations are aware of the demands that will be placed upon them so even if they play in a negative or lower-possession based team, to make the step up to NT, they have to be able to do a lot more.
Perhaps this is even an extra feather in the cap for them because it would show versatility and eclectic traits that move them from system-based to universal. I've been high on their DM's for quite some time and wondered how they've not been plundered for talent, tbh. Javi Martinez was the perfect Carrick successor for me, for example, and they have a stream of these DM's that quietly do their job with no plaudits who, even at base ends would be very good additions to higher placed teams, if not as starters then in the rotation. More important, they are cheap!
I get your main point, but I trust the base fundamentals of those raised and honed in the art to switch systems more plus, the risk is reduced because they don't cost anything like what Rice is touted for. I've not seen it in him where I look at his technical base or mentality and think he'll thrive in a team that hurts the opposition and dominates the play. Even when taking time out and watching him intently, I'm not seeing 'it'; if I was scouting for like-minded, bigger teams than West Ham, I'd be of the opposite opinion, as I'm seeing a lot in him that would thrive in that kind of set up, so it's not about him being a bad player, just not what I think comes as default from aforementioned nations, or players raised in specific leagues.