Why can NUMERIC columns not use deduplication?

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/14/btree-implementation.html
Description:

"64.4.3. Deduplication" says:

"numeric cannot use deduplication. Numeric display scale must be preserved
among equal datums."

However I don't understand this. An equal datum is an equal datum regardless
of display scale, isn't it?

Even in the special case of a NUMERIC column with no precision or scale
(8.1.2), for example if a table has an index on a NUMERIC column, and some
rows have the value 8 in that column, and some have the value 8.0 (I think
these are different values/datums in this special case), I would not expect
all those index entries to be deduplicated into a single list, but I would
expect them to be deduplicated into two lists (one for the value 8, and one
for the value 8.0). Then again I am not familiar with the actual
implementation.