Yep, the idea with a number 10 in the way Moyes and Dyche use them is that they press/cut passing lanes in a 442 out of possession and then they are the secondary goal scoring threat after the striker.
They don't typically go for your stereotypical creative number 10 because that type of player tends not to do enough defensively and, like it or not, 442 out of possession is still the favoured defensive shape for most managers - even Pep still does this a lot.
What it does do, however, is to mean you have one less man in deeper areas at times during build up play - this usually leads to one or both of your wide players tucking in or at least not being as far forward as a wide player in a 433 would be.
There are definitely defensive advantages to the number 10 mould that Moyes and Dyche employ (this isn't new for Moyes - think Cahill/Fellaini last time he was here and Soucek at West Ham - Paqueta played from the left a lot), but like any system there are ways it makes you weaker too.