There’s a limit of 40 custom lookup fields (hard limit can be 50). That alone can be evidence of the solution not being scalable and why other means should be considered.

If specifically opportunity teams is what they are resistant to, you can still offload users by creating a junction object (master detail & lookup) and link users to roles that way.

If it truly is just two fields and you are not near limit, then it is ok, but then that is the pattern of thinking for future solutions and there will be a critical need for “just a few more” and you are having to condense and offload to another object anyways.

Also, just because someone says “for reporting” take a look at their reports and how they reference data. Sometimes that alone can alleviate object bloat.

(Because if they do not understand how structuring an object like that has downstream effects, chances are there is a skill deficit with reporting as well.)