Most of the times people dont go in a finetuning process, and dont know how in the first place...
They upgrade after a long or short time moving the problem around half the time.... Upgrading is sometimes for the better for sure but when someone dont know how to optimize the S.Q. by his own means, often they forget about the sound and lives with the music and it is ok for sure....
But it is way more fun to improve, month after months, and at the end music comes from our own hands more than from a purchase that is often as illusory than it was good at first listen....So good they are any electronic component need to be rightfully embedded and no designer will like to say frankly to his customer : " you know my product is perfect but to listen to his optimal quality you must learn now how to embed it in your house"....Who would buy it thousand dollars, only to know that right out of the box the product is not at his better level of working order ? :)
The other reason is after all the electronic designer of an amplifier or a dac or of the speakers are not acoustician, physicist or electrician, and dont live in your particular house and room....They are interested in designing not in the embedding so much....Design is an idealized standardization process, acoustic of someone room is more an individualized subtle embedding process, not reducible to standardization....
After the acoustic the same is true for the particular electrical grid of your house and for the general mechanical resonance controls problem...Any electronic component vibrate and affect the other E.C. and all the audio system is affected by the vibrations in his neighborhood... These are the 3 embeddings problems to solve.....The more important fact in audio.... It is simple but nobody on any forums explained it clearly to me and I read thousand of hours to understand.....I want to be clear myself and dissipate the upgrading myths.....
For sure many reviewers speak about some products dedicated to one of these 3 embeddings times to times...They called that a tweak....But this is a long way to understand the 3 embeddings problems, in fact no one can solve that problem with a tweak or even with a few tweaks....We must be systematic....No reviewers would be invited to speak about something at all if they dared to say the truth: the embeddings of your audio system are way more impactful in your experience of Hi-Fi than the upgrading purchase of only one electronic component in general most of the times (speakers, amp or dac).... This is the upgrading myth.... :)