I don’t disagree, but Windows’ built in screen casting is hard to find and clunky to use. Linux is even worse off. Until earlier this year there was no real support from any Linux desktop environment. There’s a GNOME project that’s supposed to be putting together support. It was announced to ship with GNOME 46, but I’m not a GNOME user so I just tried to install the flatpak on my Kubuntu machine. It detects my TV but fails to connect with it. Definitely still needs work.
Helpful tip: there’s a setting in Firefox to block all notification requests. It’s under Settings > Privacy & Security, then scroll down to the Permissions heading. Click the “Settings…” button next to the the Notifications entry and tick the box for “Block new requests asking to allow notifications”.
I assume there’s an equivalent in Chrome, but I don’t know what it is off the top of my head.
Ninja edit: Removed my attempt to hyperlink directly to the relevant Firefox settings page because it wasn’t working.