§ 3. It is not lawful for anyone, without coming to the Apostolic See, to transfer to another rite,
or, after legitimate transfer, to return to the former.
This was always stressed in years gone by. We even had to get permission to attend a wedding in another rite.
Yet now, people on their own authority, not only shop rites but advise others to do so also.
You see it here on CI, people being told to go to the most convenient.