People are usually looking for a combination of 100% uptime, the ability to configure DNS on your LAN (ssh dhcphostname, and/or pi hole), light virtualization (x86 routers with power consumption similar to a raspberry pi are available), security, etc.
Also, with your TP-Link, your ISP has administrative access to log into your home LAN, and poke around. They might give themselves the right to do so in their TOS, or they might have hired a malicious employee, or suffer a security compromise.
Also, with your TP-Link, your ISP has administrative access to log into your home LAN, and poke around. They might give themselves the right to do so in their TOS, or they might have hired a malicious employee, or suffer a security compromise.