I think the matter of lists is orthogonal to the issue of global directories.

I have ... well, not quite nothing, but little against the concept of email lists. They're useful. I've used them extensively. They don't, of and by themselves, address numerous other problems with email. And they can and do insert a few of their own.

Regards lists and directories, I'm not entirely sure what your argument is, but I can interpret your comment at least two ways:

First, an email list is a directory. Yes, it is. It is not, however, a global one. In the right contexts, a list can address the question of discoverability, but that's somewhat secondary. There's the question of what mail is or isn't allowed on-list (e.g., is it open to all senders, or subscribers only?). Service lists -- the effective utilisation of addresses such as postmaster@ or webmaster@ -- typically have to be fairly widely open. This creates some well-known issues, mostly having to do with spam, but also of privacy and organisational confusion over who should or shouldn't be receiving such messages, or how they ought respond. For many corporate distributions, the names of such lists are not generally advertised outside an organisation, though likely targets include "all@", "sales@", "engineering@", etc. Again, this can be useful or not.

The other point you seem to be making is that an organisation can automatically manage its own lists through directory systems. Again, this is addressing the concept of a directory of directories, and any one of the (sub)directories might choose to expose or conceal elements to specific entities. Nothing in any of this is required or constrained by what I've written above.

More generally, you seem to be addressing the question of discoverability, which is a general one. The idea that organisations with their own individual entities might have or conceal means of reaching or contacting people is an old one. I'd call it the introductions problem.

An anecdote from personal experience. At various times, I've had an interest in contacting specific people at organisations. Two come to mind -- an IBM director over a matter somewhat concerning the company, and an issue involving spam transiting a Microsoft-run service. My general biases are that I'm favourably inclined toward IBM, and unfavourably toward Microsoft.

In each case, I found a general switchboard phone number and called, asking for the individual by name.

In the case of Microsoft, the operator said "just a moment", connected me through, the director picked up on the first ring, we had a brief conversation where I described the problem (about five minutes or less), he said he'd get me in touch with the person I needed to talk to, took my number, and within fifteen minutes I was talking to the manager in charge of the unit. We worked on the issue (I had better information than him) for a few months whilst they resolved it, quite measurably.

In the case of IBM, I was connected to an administrative assistant who said, and I think I'm quoting directly, "You can't talk to him, he's a director".

I'm struck by the difference to this day. Much as I don't care for Microsoft, my impression is that they know how to run a business and to transmit information. On the other hand, IBM may have its reasons for sheltering its upper-level management. I suspect otherwise.