I agree with this 100% as a general philosophy. The strength of a team lie in its core. That said, there's a difference between artificially trying to improve in the standings by hiring a bunch of mercenaries and creating conditions for the said core to develop organically.
Some examples:
Our first line could come back all guns blazing, but it's not going to help our penalty kill, which will lead to goals against, losses and impact on team morale. Is Rafael Harvey-Pinard the best we can do on our bottom 6? I doubt that. Is there someone in Laval who can step up? Perhaps.
Newhook - Dach could be the nucleus of a good line, but is it necessary, in the name internal development, to staple Josh Anderson on that line? Wouldn't a Tarasenko, a Perron, or an Arvidsson be a good support player on that line, increasing its chance of success? It's not like Dach has established himself the last two years and is ready to run the show coming back from a season-long injury. Maybe the bosses know how to get Anderson going. Fine. They know the players. It's their call.
Is it good developmental strategy to press Joshua Roy into a role he might not be able to handle?
Again, I agree with you in principle, but patience should not lead to passivity.