2.4GHz wifi is not suitable for two big reasons, interference and low bandwidth. 2.4GHz wifi in any kind of suburban or city environment and sometimes even in rural will be congested with other networks, microwaves, other appliances, etc causing massive speed degradation or fluctuations. The range of 2.4GHz is just too large for all the equipment that uses it in today’s world. In my previous apartment complex for example my phone could see 35 distinct 2.4GHz wifi networks while only 3 at max can operate without interfering with each other. In that same building i could only see 13 5GHz networks. Which brings me to the second issue of bandwidth
2.4GHz at least here in the US only has channels 1, 6, and 11 that will not interfere with each other. if anyone puts their network between these three channels it will knock out both the one below and the one above. Channel 3 would interfere with both channels 1 and 6 for example. By going up to 5GHz you have many more free channels, fewer networks competing for those channels, and higher bandwidth channels allowing for much higher throughput. 2.4GHz allows 40MHz wide channels which in isolation would offer ~400mbps, but you will never see that in the real world.
Personally, i think OEMs should just stop including it or have it disabled by default and only enable it in an “advanced settings” area.
Edit: I am actually really surprised at how unpopular this opinion appears to be.
What are your walls made of? Mine are steel reinforced concrete. Standard building material where I live, since timber is just too expensive here.
Also I have three buildings (house, workshop, garage) on my suburban property and would like access in all three as well as out in the garden, since that’s where I spend my weekends.
Also, I’ve just never seen the overcrowding issues a lot of people complain about. Maybe because we have different building materials here. 2.4Ghz will go through a concrete wall, but it loses a lot of power… and there’s at least two of them (plus a good sized air gap) to my direct neighbours.
My access point does both 2.4Ghz and 5Ghz at the same time. When I’m in the same room, I get 5Ghz. Walk through a doorway… it seamlessly switches to 2.4Ghz. You don’t have to choose one or the other. You can do both and it will (if setup correctly, which mine was by default) pick the one with the strongest signal.