I do not think using the Antibiotics is much of an issue unless the countries prohibit it over the counter. Then you have fewer options.
So they can be used in place of the black out, and the post treatment will last about 1-2 months before BGA comes back, or the aquarist has fixed the issues by then etc. With the 3 day BO, many think only to do the BO, not the KNO3...............and the BGA comes right back.
Not so with antiobitotics, but with antibiotics, you do not/cannot tell if you fixed the underlying cause. Which is more important to aquatic horticulture than simply killing BGA.
The goal is growing plants well, not killing algae:grinyes:
Regards,
Tom Barr