Great article. Very well articulated.
In addition to points raised here would add another three big picture/high-level points of why this is happening:
In the world of Financial Services, compared to lending and other products, Payments:
- Has most frequent touch points with consumers and SME merchants — Big tech companies have superior skills and experience in designing products and services which have frequent customer interaction points
- Is most technologically intensive — Big tech possesses superior infrastructural capabilities to compete
- Is least capital and regulatory intensive — least barriers to entry

This makes this industry very attractive for technology players and puts them in a strong position to compete against banks