Yeah, absolutely. But that's not really what the term refit means.
And if that is a refit in Starfleet parlance -- as the instagram log claims it is -- than what prevents the Lamaar-class Voyager from also being a refit. Keep in mind that in "The Star Gazer", Picard claimed that the new Stargazer was also a refit, and, according to Matalas, it was a refit of the Constellation-class Stargazer:
"Like the TMP Enterprise, it’s a massively updated refit. I like to think of it as the story of the broom: If one day you replace the handle, and another day the brush, is it still the same broom? We thought of it as a vessel endlessly repaired and upgraded, brought in-line with current-future tech, so that somewhere underneath all the lights and polish are the bones of Picard’s original ship. Does it make sense? I don’t know. But I sure like the spirit of it."
Now, personally, I would prefer to not take anything Terry Matalas says seriously, but a lot of people seem tot think he should be Trek's new torchbearer, so there's a good chance we'll see a lot more of this nonsense in the future.
I don't think either of us are arguing against the Federation reusing old components.
The only point of contention is that you were sceptical that the Voyager A could be a refit of an Intrepid-class starship due to the size disparity, and my argument is that, even though I am personally not a fan, the was the current crop of Trek showrunners have decided to use the term size doesn't really matter with regards to what is or is not a refit.