The announcement of the planned competition led to a huge backlash, including from governing bodies, rival clubs, fans, players and media, leading to the majority of the teams that had signed up making a quick U-turn.
UEFA issued fines to Atletico Madrid, Inter, Milan, and the six Premier League clubs – Arsenal, Chelsea, Liverpool, Manchester City, Manchester United and Tottenham - but a court ruling meant disciplinary proceedings against Barcelona, Real Madrid and Juventus, the three founding members yet to cut ties with the Super League, had to be halted.
A preliminary injunction was granted by a judge in Spain, with the case heading to the European Court of Justice.
Barca president Joan Laporta recently said his own club will not apologise for "wanting to be the owners of our own destiny", while he also insisted the project remains very much alive.
However, speaking on a media call on Thursday, Tebas made clear Barca are incorrect to make such an assessment, considering the mass exodus.
"I've spoken with Barca executives in recent days. They believe they should keep doing what they're doing and I think they're wrong," Tebas said.
"The concept of the Super League is impossible. Nine of the twelve clubs have asked to dissolve the company they founded."
He said: "The model they're defending, without the English clubs... I think it's dead.
"Laporta says the courts have said they're in the right, but that's not true, it's one judge in Madrid and an injunction.
"I've tried to convince them that they're wrong and should work along other lines."
Tebas was also asked about Lionel Messi's future, making clear Barca will not be allowed any leeway in terms of LaLiga's salary cap to make sure the superstar remains at Camp Nou.
Barcelona has already been busy in the transfer market as it reshapes its squad, adding forward duo Sergio Aguero and Memphis Depay on free transfers, as well as centre-back Eric Garcia.
"LaLiga has its rules and Barca know that. They know that they have to lower their salary costs by a lot," said Tebas, who hopes to have stadiums 60 per cent full when the 2021-22 season begins, despite the continued impact of the coronavirus pandemic.
"Messi is the same as Sergio Aguero or anyone else that they are adding. We will not make any exception for Messi to stay here."