Why do tenkeyless layouts dominate over "nav-less" designs?

[spremino]

From a functionality point of view, a nav-less layout keeps all keys. The numpad can already act as a navigation block, but the navigation block cannot replace the numpad.

The only explanations that come to my mind are that TKL is easier to manufacture as a cut-down full-size board, or that many users simply prefer a dedicated navigation cluster. I am curious what other reasons people see, thank you.

[Findecanor]

Unfortunately, it is rare that programs support key combinations with modifier keys on the numpad.
So you can't always select text and/or jump to next/previous word or top/bottom of document using the numpad the same way as with the dedicated arrow keys.

I've learned that the space around the inverse-T cluster matters for people. it helps people locate it.
Even some 65% and 75% layout keyboards have space around the arrow keys for that reason.

The inverse-T is IMHO superior ergonomically to the cross-layout embedded in the numpad. When you rest your fingers on the cluster, the middle finger — being longer — has its natural resting position in-between the Up and Down arrow keys, with equal distance to both. The numpad could be improved if the Numpad-5 key was an additional Down key, but I've never seen support for that.

I have become accustomed to having Home/End/PgUp/PgDn above the cursor keys. I use them all the time for editing text and code and wouldn't want to be without them.
I have a couple keyboards where the nav cluster above the cursor keys are 2×2 or 2×3, and the entire keyboard being one column less wide than a typical TKL, and I have had no problem going between that and a TKL.

There are lots of 65% and 75% keyboards that don't even include the full for nav keys, but instead have Ins and Del, or Del and PageUp, or PageUp/PageDown. Many even lack a Del key. I would never buy such a keyboard.

[fohat.digs]

Many even lack a Del key. I would never buy such a keyboard.

Hear, hear. "Delete" is one of the most often-used keys by my right hand. Do I make a lot of mistakes? Maybe.
 

[Findecanor]

BTW. There have been a couple keyboards which have overlaid inverse-T arrow keys and nav keys on top of a numeric keypad.
One of them was the Cooler Master CM Storm Quickfire TK from 2012:

[HungerMechanic]

Yes. The "Nav. Cluster" is ergonomically superior.

I can use the numpad for the same functions, but the Nav. Cluster is faster and easier.

I don't buy anything without a Nav. Cluster, unless I am looking for something very compact. That's why I have TKLs. I have a 70% board, but I find myself wanting the F-row.