Maybe we should start by identifying the exact issue. How do you define this "Bitcoin scalability problem?"
Thanks for your comment. I would describe Bitcoin scalability problem as (correct me if I am wrong) - inability to process a large number of transactions (like for example VISA). which result in impossibility to implemented Bitcoin as normal daily payment method for large amouth of people.
Achieving VISA-level scale was never a realistic goal for the base protocol. The costs of global decentralized consensus are simply too high. Bitcoin is robust as a P2P protocol because of its redundancy -- every node processes every transaction. Adding endless throughput to the base network would make it impossible to run a node, destroying that redundancy. Not to mention the increased costs for miners due to block orphaning, which would encourage mining centralization.
That's why developers and the community have opted to minimally increase throughput on the base network while building interoperable networks (like Lightning) that can deliver exponential scale with minimal added costs.