You need to use their leased modems to provide static IPs, I was told this directly from their sales team.
So a 14.95 a month suddendly becomes 14.95 + modem rental fee.
Be forewarned, the modems comcast supplies are generally buggy and have problems with crashing, hanging, et al. I'd go the dynamic route and save yourself some money.
The party line is that the modems have the static subnet configured into them then generate routing advertisements back into the Comcast network. I guess they feel that if they allow 3rd party routers that jerks will 'accidentally' configure larger subnets than they were allocated, in hopes of ducking the fees, which might stomp on adjacent customers.
And of course the fact that over many years you more than pay for the cost of the modem many times over, is icing on the cake to Comcast.
I haven't observed the bugginess issue of the routers. I self host also and I have a back door low-speed DSL line, if I need to I can remote into a router on that line then connect to a remote power switch and turn off and on the cable modem.
I agree with you.
To start , they should stop using RIPv2 and use OSPF. This will allow them to do route filtering on their side and prevent any route poisoning from hapening. If they don't like OSPF they could even do iBGP with customer auth and route filtering.
There are more than one solution to this problem and forcing the user to rent the low grade gateway (full of bugs) because they can't get their act together for business customers.
I think one of the reasons is that they can rip of static ip address owners with increasing rental prices of the modems. This way is a stealth increase to prices even though you may have locked yourself or thought you locked yourself into a contract price.
This is criminal in my mind and unfortunately I have been caught by this.