Of course, we’re making assumptions here, as we don’t know for sure that Wong suggested Strange was incapable of such a spell.
No disrespect to Wong, but let’s remember who he’s talking to.
As mentioned, Wong (who will also appear in Shang-Chi and the Legend of the Ten Rings) deliberately warned Doctor Strange in the Spider-Man: No Way Home trailer not to perform the spell, adding that it was “too dangerous.”