The megacorp argued that because Schrems set up a Facebook page - where he lists information on his lectures, books and panel debates - in addition to his personal account, his use of the social media platform is professional.
Mr Bobek's opinion states that Mr Schrems' case would be limited to his own personal claim and that he is not entitled to bring a class action suit against the USA tech giant.
The EU Court was asked to rule on the two questions by the Supreme Court in Austria handling Schrems case against Facebook Ireland for violations of privacy and personal data protection.
The PhD student has been embroiled in a years-long battle with Facebook over its privacy policies and data-sharing with USA spy agencies.
A run-in with Facebook is nothing new for the activist, who was responsible for bringing the case that resulted in the EU's highest court declaring in 2015 that Safe Harbor, the US-Europe data-sharing pact, was illegal.
Mr Schrems had been seeking to claim 500 euros ($586; £448) in damages per person for about 25,000 people.
The EU Court of Justice's advocate-general found that Schrems could not add people from other countries to his case, as this type of worldwide collective action is not possible in EU courts.
Schrems responded to Bobek in a statement, noting that because European Union laws allow citizens to move home countries any time they choose, their home court can change just as easily.
Schrems said that this opinion was "unfortunately hard to understand", and countered that if people were to bring separate cases this would drive court costs up for everyone.
Facebook commented on the Advocate General's opinion.
Class action suits, in which many people sue together, are not as common in Europe as they are in the U.S., but Schrems argued that individual Facebook users could not afford the legal costs of individually fighting their cases against the Silicon Valley tech giant.
"The outcome would be that thousands of courts in the whole European Union would have to deal with an identical, but local lawsuit against Facebook", he said.
For its part, Facebook has limited itself to saying: "Today's opinion supports the decisions of two courts that Mr Schrems's claims can not proceed as "class action" on behalf of other consumers in Austrian courts".
Schrems concluded: "In this case we would be in a situation where citizens have rights on paper - but no realistic option to ever defend their rights in practice".
"I hope that the five judges that will ultimately decide over this case will take a closer look", he said.