narc0tic_bird , 4 hours ago

What you’re describing as “DisplayPort alt mode” is DisplayPort Multi-Stream Transport (MST). Alt mode is the ability to pass native DisplayPort stream(s) via USB-C, which all M chip Macs are capable of. MST is indeed unsupported by M chip hardware, and it’s not supported in macOS either way - even the Intel Macs don’t support it even though the hardware is capable of it.

MST is nice for a dual WQHD setup or something (or dual UHD@60 with DisplayPort 1.4), but attempt to drive multiple (very) high resolution and refresh rate displays and you’ll be starved for bandwidth very quickly. Daisy-chaining 6 displays might technically be possible with MST, but each of them would need to be set to a fairly low resolution for today’s standards. Macs that support more than one external display can support two independent/full DisplayPort 1.4 signals per Thunderbolt port (as per the Thunderbolt 4 spec), so with a proper Thunderbolt hub you can connect two high resolution displays via one port no problem.

I agree that even base M chips should support at least 3 simultaneous displays (one internal and two external, or 3 external in clamshell mode), and they should add MST support for the convenience to be able to connect to USB-C hubs using MST with two (lower-resolution) monitors, and support proper sub-pixel font anti-aliasing on these low-DPI displays (which macOS was perfectly capable of in the past, but they removed it). Just for the convenience of being able to use any random hub you stumble across and it “just works”, not because it’s necessarily ideal.

But your comparison is blown way out of proportion. “Max” Macs support the internal display at full resolution and refresh rate (120 Hz), 3 external 6K 60Hz displays and an additional display via HDMI (4K 144 Hz on recent models). Whatever bandwidth is left per display when daisy-chaining 6 displays to a single Thunderbolt port on a Windows machine, it won’t be anywhere near enough to drive all of them at these resolutions.