The apparent objection to your statement by another poster regarding no practical consequences derives from the difference between an extant sapient entity’s point of view vis-à-vis objective reality.

That is, extant sapient entities (principly meaning us) already exist. We are aware of our own existence, and hence the question of our existence is a non-issue. We naturally take it for granted, since it’s not an issue we have to worry about (at least in the immediate sense of the here and now; in the temporal sense we have to provide for our future if we wish to continue to exist in near to our present form).

But what quantum mechanics tells us is that existence necessarily exists as a multiverse, and that we wouldn’t even be here to ponder on this issue were it not for the multiversal nature of reality. Hence, we owe our existence to the multiversal nature of existence.

So in the objective sense, this issue has fundamental and profound practical consequences: one practical consequence being that we wouldn’t exist if the multiverse weren’t true.

Of course, given that we do exist, the realization that we (in part) owe our very existence to the multiverse nature of reality may not in of itself bring us a cornucopia of new technology and wealth (i.e., what we, as already-extant entities, are naturally inclined to regard as “practical,” i.e., things which affect us and our development beyond what merely makes our existence possible). But it is an advancement of knowledge, and the closer we come to understanding reality, the closer we will be able to come in manipulating reality to suit us.

“The many worlds interpretation of quantum mechanics asserts that everything that could ever happen has happened and is happening and will happen across a vast — possibly infinite — number of parallel universes. If this idea were to be confirmed, it would arguably be the greatest scientific discovery of all time, even though it wouldn’t have any practical consequences.”