This is true. Debian Linux currently doesn't load non-free firmware ("blobs") for your system GPU, WiFi and other devices. Other popular distros like Ubuntu and co does it by default at installation time. The current method is to enable non-free repo in `vim /etc/apt/sources.list` and then run `apt-get update && apt install firmware-${name-here}`. I hope this proposal gets approved. So that new users find it easy to load those "blobs" for their devices at install or run time via teh TUI/GUI/CLI option.
Debian has a non-free installer that does install firmware blobs, but it isn't the default installer.