Nobody is claiming that. I guess what you fail to understand is, that EVERY additional single use port comes at the expense of something else (volume, thickness, battery life, other ports, etc.).
So does EVERY USB-C/TB3 port. Each full-featured USB-C controller requires the equivalent of 4 PCIe lanes (either external or internal to the SoC) and 2 DisplayPort streams (or the switching needed to share them with other controllers), plus the plumbing needed for power supply and plumbing. Alternatively, you have the fugly mess of different functionality on different so-called "universal" ports.
The sort of "single use" port facilities that people are asking for - 1-2 USB-A connectors, 1x HDMI, maybe SD could be implemented with less I/O resources than adding more TB3/USB-C.
Then, switching to Apple Silicon has the potential to reduce battery consumption, reduce the number of components on the mainboard (look at the M1 teardowns) and reduce the space needed for fans/heatsinks. Apple also gets to re-think how much I/O the chip requires, and whether the desktop/mobile distinction that Intel made (Intel mobile chips tend to have limited I/O c/f desktop). Possibly, even the cases are getting re-designed. So the designers should have a potential space/power/battery/IO bonus to divvy up between TB3, "single-use" ports or thinner laptops.
Then there are other constraints - e.g. you can't make the laptop smaller than the display, and the 16" MBP already has the highest capacity battery that is allowed in airplane hand luggage.
So this is simply not a case of taking things away from the Intel Macs - there's a reason why these rumours coincide with the switch to Apple Silicon and other rumours about major re-designs.
Designing a single product to satisfy a large number of different users always means making
compromises, which doesn't always mean going for the maximum theoretical capacity in a perfect world with hot- and cold- running Thunderbolt. People buy computers to solve real-world problems, not win at Top Trumps.
Plus, there are new capabilities - TB4 (...and the updated TB3 used in the M1 Macs) allows for Thunderbolt hubs - add one of those to a 2-Port Air and you're close to the capability of the current 4-port models. Also, everything is moving to DisplayPort 1.4, so you no longer need 2 DP streams for a 5k or higher display... So while I doubt that they
will reduce the high-end MBP to 2 ports, it wouldn't be such a disaster (...because it's silly to complain about needing hubs/docks etc. and being able to 'dock' to 3 devices with a single cable is good, right?)