Please see #29719

Please re-open as #29719 is now closed as not good enough

@PhilETaylor
Although it was closed. I think the solution is #29719 (comment)

Please post there your opinion.

I made a PR which is not exactly doing what @PhilETaylor requires, but is easy to modify to avoid the overload by the other one:
#29721

The filesystem plugins are meant to be the DEFINITIVE PLACE that the Media Manager can use to access media.

The "local" filesystem folders select and thus should be the DEFINITIVE folders that user-selectable media can reside in locally. Not everyone will want to use /media or /images and so any folder within the local web-accessible file-system should be selectable. (It would also be nice for folders to be subject to ACL too, but that's not implemented either)

The plugin approach improves security and to allow additional plugins for media (e.g loading from dropbox/AmazonS3)

However, the Joomla project (JSST Team) has already rejected correctly implementing this to ensure that all places in Joomla ONLY use the media plugins /facepalm/ and therefore the whole concept is now null and void and its "just another half baked idea" only implemented in "some places" and not others.

doing what @PhilETaylor requires

Might be lost in translation, but I dont personally "require" anything, I am simply pointing out the current limitation in the current plugin and saying that its not good enough to only have a list of the root folders (most of which have nothing to do with media) and not be able to select any other custom folder within the local filesystem.

Hmm I also dont have Github permissions to reopen my own issues now.

I understand the limitations you point to.
Whether it is possible to add this feature and keep also what we have now (anyway should be modified as proposed in #29721 as indeed proposing all core root directories there makes no sense) looks like needing a total refactoring of the plugin and com_media.
I tested by modifying directly in db the possible plugin directories params (for example by using components/mycustommedia) and although the directory exists in Media, it does not display subs nor images.

It has always been possible to have a folder other than /images as the root folder for the media manager

Yes, in J3.
Have you even tried in J4: it's impossible as it is the plugin which has priority over the Media Options... In J4, only a root folder will be usable.

just do that

Yes I know - I raised an issue about those fields being useless now.

J3: