Sadly, this occurs far more often than you might think. Large companies especially do it to themselves given how they structure their teams with developers and DBAs being on different teams and reporting to different managers. (i.e. you can trace their respective management chain separately until just below the C level) These reporting structures are problematic since large companies tend to hire people with very narrow skillsets which makes it vital that these groups work together. The end result is that you have teams throwing things over the wall to each other not knowing or caring what is happening on the other side of the wall... dysfunction by design.
Funny story: at a, let's say, Fortune 50 tech company there was an investigation into why performance for a certain database query had become atrocious. The problem was that the query was against a table that started out quite small and then grew very large. And the database had been configured to use "query plan stability" to improve predictability of performance. However, the query plan that the db originally came up with for that nearly empty table was a full table scan, which was actually the fastest method under those conditions. Yet it continued to use a full table scan even as the table grew to many tens of millions of rows. It was a simple matter to switch the query to actually make use of the indexes that already existed.