TL;DR: it doesn't quite work[1].
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>Portamento is a fairly standard feature
On monophonic synthesizers.
There's no standard on how that would work with polyphony (that would be pretty much equivalent to polyphonic pitch bend). With your trick, you'd still need to specify which note goes to which new note with portamento/glide, and there is no standard for that.
The problem is usually worse with analog gear, where oscillators are commonly assigned to keys via a round-robin scheme. So enabling polyphonic portamento means that even if you play the same chord over and over, you'd hear the notes slide! Not quite what you intend.
So while some polyphonic synths have portamento/glide in poly mode, lack of support in the protocol means that it acts unpredictably: you only have control of where the notes are sliding to, as a set.
You can see the problem very clearly, using Behringer Deepmind 6 (6-voice analog with poly portamento) as an example here[1].
At this point, you break out your polyphony into voices, put each voice on its own track / MIDI channel, and pitch bend / portamento that (and record separately, if needed). And then you have the ROLI solution. Which is not compatible with any other MIDI controller.
As I said, MIDI is hackable enough to allow one to do pretty much everything, but it's going to be non-standard. And standards and defaults matter.
For that matter, that's why we have MPE[2], which is an extension of MIDI, but it's very, very new (2018-new).
[1]https://www.youtube.com/watch?v=o9cvMCHgB2s
[2]http://www.rogerlinndesign.com/mpe.html