MC-204428 indicates this is intended. The issue it duplicates indicates the reason being that all requests for blocks to be/not be waterlogged are feature requests/parity issues.
May also be a chance to clarify if this is the same stance for Bedrock.

Thank you for your report!
We're resolving and linking this ticket forward as a duplicate of MCPE-121539, as that ticket contains more detailed information and/or has already been triaged by Mojang.

If you would like to add a vote and any extra information to the main ticket it would be appreciated.

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