Doing actual things in the real world is the *only* possible "semantic grounding".
I don't mean this figuratively or even "for all intents and purposes" (though the latter should suffice anyway.) This is literally and fundamentally true.
No matter how clever you think your code is, the minute you actually have to run it you almost always see just how wrong-headed your original idea was.
But computer programs are an extremely special case, and evaluating whether an idea works or not is rarely a straightforward enterprise (even in software there's still the area of user experience where the desired outcome is somewhat nebulous.) Nonetheless, the fragility of human knowledge reveals just how worthless opinions generally are.
The only solution is for thought to be grounded in praxis, that you can only access some kind of robust truth by mucking around in the dirt and tinkering with whatever is at hand in search of degrees of freedom.
I'm especially convinced for this reason that philosophy can't survive without art; that art (in the broadest sense of the term) specifically gives texture, embodiment and semantic grounding to ideas that would otherwise quite literally not make sense.
Praxis creates sense, and philosophy lacks sense in the absence of a material counterpart. Wittgenstein believed metaphorical statements to literally not possess any logical sense; he was correct, but only under the assumption of a vacuum. All discourse of dimension > 0 has to pass through a material substrate.