On my Mod-DH/Colemak-DH pages, I'm not aiming to present a comprehensive guide to the Colemak ecosystem and the history of mods. Nor should I, the aim is to present a clear guide to that one mod. Of course, that doesn't mean I don't fully acknowledge the prior works on which it depends: Colemak itself, the angle mod, and yes, even Workman!

I think that azuvix's point is more that the wide mod and Extend are both complementary to *any* layout, and so are "add-ons" in the sense that you choose your base layout first, then you might investigate further what's out there, and end up adopting these also.

In a non-angle-mod "common base", how would that work if you are using Colemak-DH? Would you use traditional fingering, and have D in the Qwerty V position? To my mind, that would go against the mod's whole philosophy.

There is kind of a "common base" for ANSI already, it's the variant with Z in the Qwerty B position.

Let me see if we understand each other correctly:
• You cannot apply Colemak-DH without an Angle mod, as they are intertwined. This is why I also call it Curl(DH)Angle.
• I do agree that the Angle mod is a kind of "add-on" or module in the sense that you can choose between different solutions.
• But it's still a necessary requirement for Colemak-DH!
• I would be strongly against choosing ANSI over ISO as "THE" standard! They both exist in large numbers, and I prefer ISO anyway.

• Whether to include the Wide mod in the standard package or not is indeed open to discussion.
• My choice to do so is based on the observation above that Colemak-DH requires more "geekiness" and dedication.
• Therefore, to avoid being overworked I've opted to primarily deliver the two main choices of Vanilla or Full Package (CAW).
• I'm probably going to still supply (A)Wide without DH and DH without (A)Wide because I'm a perfectionist... and overwork myself... ;-)
• I'm not arguing against providing Colemak-DH without the Wide mod as such! I'm merely making choices for my packages.
• In the presentation of Colemak-DH I think it shouldn't be mixed with WIde or other unessential mods, to keep things clear.

Yes, they are intertwined, because otherwise D is not in the good position for the standard keyboard. But just as a side note, not pretending to be a mainstream, I'm using the split columnar staggered keyboard to which neither Angle nor Wide mods are applicable to, and changes of Colemak-DH for me are effectively just moving letters in the middle columns.   

Yes, and I myself started with just Angle mod applied to vanilla Colemak.

For the standard row-staggered keyboards, see my previous point.

I have the same feeling, ISO board is a perfect fit for Colemak-DH. But it is more rare than white unicorns in USA. Many people from ANSI side will just turn away as soon as they see that ISO board is required to use the mod.

I vote for simplification and less number of options in the "introductory package". Just Angle mod and letters moved around looks good.

One more comment I have regarding the matrix/columnar boards. I think that in sake of unification we should not promote a special mode for matrix/ergonomic keyboard as it is mentioned at the bottom of the page at https://colemakmods.github.io/mod-dh/keyboards.html
M in the middle or M in the bottom row does not worth the schism, whoever want to do further custom modification of the layout can always do that themselves. M in the bottom row of the matrix board or even Ergodox is really not a huge inconvenience (and I'm using such boards exclusively for almost a year now). I used to use M in the middle for some time, and I'm not quite sure that it is for better though. This is something basically wrong about "qwerty H" position in Colemak because whatever you put there will create inconvenient to use bigram with E.  ME and MN bigrams happens more often than KE and even KN, this is my point that K in the middle is better. Also, with this version K and M remains in their qwerty rows, which is better for using sculptured keycaps for mechanical keyboards, Colemak version is possible to buy, Colemak-DH obviously not, but there are only 3 caps required for it in addition to Colemak, D and H in bottom row and B in top row, so I hope that one day I will be able to have Colemak-DH sculptured keycaps. :)

Yeah. My stance on the M-in-the-middle variant (Colemak-DHm) is to make it available but not on the "front page". People who need it should have access to it, but I won't promote it (much) to avoid confusing newcomers.