If your provider has implemented it (Comcast is the only one i know of in north america) then Active Queue Management is a huge quality of life improvement that you won't know you were missing unless you already had a router that implements queue management. https://www.cablelabs.com/blog/how-docsis-3-1-reduces-latency-with-active-queue-management

Not buying another modem when the ISP quietly upgrades the CMTS and makes more speed available in your neighborhood.

Yeah I recently switched from cable to fiber (finally available), and prior I was using an old as fuck modem/router that capped at 500Mbps. My internet at fastest was 380. I rarely transfer files over the network, so figured why bother? (I did have Gen1 Google Mesh though to cover dead spots). I had a bit of a shopping splurge when I got fiber. Nothing crazy, just an upgraded mesh and a switch (Why the fuck does Frontier provide an ONT with 8 ethernet ports but only one is active?)

At least in my case, my DOC IS 3.0 modem was having connectivity issues. My neighbor in another apartment had similar issues: dropped connections, slower than expected speeds, etc. Switching to DOCSIS 3.0 modems solved the problem. I guess Comcast upgraded their hardware and it wasn't compatible with my modem anymore

Because docsis 3.0 standard is nearly 20 years old at this point and 3.1 is significantly faster. Docsis 3.1 is only 15, but 4 (which is still 8 years old) probably isn't supported by your ISP yet. But the speed difference is quite noticeable. 3.0 will theoretically do 1gbps down, and 100-200 up, but 3.1 could do 10 down and 1gbps up. In the age of symmetrical fiber internet those upload speeds are dire. 3.1 realistically gets you a symmetrical gig connection.

In my neighborhood you get a choice between coax or nothing.

Can confirm, I live out in the countryside with only coax available, and a measly 1Gbit down 150Mbit up and 9 - 11ms ping. No caps.

Wait, that’s awesome and steady and reliable. Expensive sure but with heavy multiperson usage and no noticeable issues, I am wondering WTF you’re on about unless it’s some weird edge case?

Maybe you are referring to predatory business practices like oversubscribed lines? That’s not a technical problem.

I still use coax because I buy internet from a reseller third party and this is what they have. I have 400/50 for 35$, which is a lot cheaper yhan the competitors. No reason for me to change.