[evanelias]

You're over-stating the issue. You can always simply try ALTER TABLE ... ALGORITHM=INSTANT first, and this will just return an error immediately if the requested alteration doesn't support instant changes. Not a land mine at all.

The article is also four years old, and INSTANT now covers a few additional cases which it didn't at that time.

If your alter doesn't support INSTANT, at that point you can fall back to an online schema change tool, of which there are several battle-tested options. All of the largest MySQL users (including many of the biggest names in tech) do schema changes any time of day without issue by automating these tools. In comparison the equivalent tools for Postgres are far less mature.