That's clearly not what was meant, even without the context of this following bit:

> To describe tones that exist in music, we can describe tones that exist on a piano. There are only two rules:

> the first key must play a tone of 27.5 Hz each next key must play a tone 6% higher than the previous key

(This is not to mention that at a 1.06x increase per half step you're going to be sharp by 1 cent / octave which starts to add up).

Of course you can, but that's not what's implied by the quote.

In addition to microtonality, many instruments (and the human voice) are capable of infinite tuning, and musicians will deviate from the "correct" note (as played by an even-tempered instrument) based on chord structure, voice leading, etc.

Aside from that not being what was said (the parent’s pull-quote is wrong in multiple ways), it is in fact not possible to tune a piano to any arbitrary set of 88 pitches without changing the design so dramatically and fundamentally that it would no longer be a piano. The triangular shape of a grand determined by the strings lengths, the placement of the pins, the use of double/triple strings in some frequency ranges, and design of the sound board, all permit only a very limited range of frequencies for each key on the keyboard. You very obviously cannot take an existing piano and tune it to 88 keys of A0, nor to 88 keys of C9.

there are absolutely pitches that an arbitrary piano cannot be tuned to. it is also non-trivial to tune a piano.