Having a data lake - which I understand as a repository of raw data of diverse types, regardless of the tools - structured in a tool like S3 is very useful when you have multiple use cases over data of different kinds.
For example, you could store audio files from customer calls and have them processed automatically by Spark jobs (e.g. for transcript and stats generation), structure and store call stats on a database for analytics, and do further analysis via notebooks on data science initiatives (e.g. sentiment analysis). This is akin to having a staging area for complex and diverse data types, and S3 is useful for this because of its speed, scale and management features.
Teradata or Snowflake aren't a great fit for use cases like these, but they are great if the use case is to get answers to questions like "top 3 operators per team in volume of calls, by department and region, in last quarter" if the volume of calls is big.
If I understood correctly, I think your comment was more focused on why use new tools when the existing are mature, but I think big data tools have had to become more specialized and targeted for specific use cases. But if the question is "why build more than one data lake", the only reason I can see is organizational: teams or different areas of an organization either need their own data lake because they have specific needs (which is rare) or won't/can't collaborate with others to have a shared asset.