Then disable it. It's a preference option that can be used to express yourself or even indicate things in your layer configuration.
I switch backlight colors based on layout. The default typing layer is in my favorite shade of blue, then when I'm on my "ide shortcut/F-key layer" then it switches to a complementary share of orange. When I'm on my "common shortcuts/media control" layer it switches to purple for valid shortcut keys while the media keys have their own color layout to more quickly indicate where back/fwd/play/mute is.
No one says you have to use unicorn vomit colors or a constantly shifting color pattern. But it does look good in a demo and does a great job of indicating that it's not a solid color.
I have a key that toggles between keyboard layers, of which there are three. Different layers are assigned different colors. If I forget which layer I'm on then I can just glance at the keyboard and know. The LEDs are similar in purpose to a Caps Lock indicator.
And for the third layer, which has only a dozen or so keys defined, the keys that are defined are lit up in their own color. This layer sees less use than the first two, so it is helpful guidance to remember which are defined.
I have criticisms about the keyboard -- Moonlander -- but none are about the LEDs. The LEDs are useful and not simply moronic eye-candy as you seem to imply.
I don't mind them in devices like this, where the configuration is built into the device firmware. Where I found it incredibly frustrating was with the Razer laptops, where the rainbow stream would run constantly until the Synapse software finally launched and it switched to your preferred configuration. I wish default on some of these devices was just basic white or off to keep from running into issues.
Not only that half the RGB keyboards fuck out fairly quickly or have power and USB problems.
Electric truck nuts. That's all it is.