In a post on SqlServerCentral.com, it is mentioned by several people that the files for the Resource database (mssqlsystemresource.mdf and ldf) should be placed in the same folder as the master database file. This was for SQL Server 2005. Is this still a recommendation when it comes to SQL Server 2017? I tried looking in BOL, but could not find any mention of this there.
Totally agree with what George has mentioned, just trying to shed some more light to make it clear.
For SQL Server 2005
You were allowed to move resource database. If you read SQL Server 2005 Master Database Document it says
The Resource database depends on the location of the master database. If you move the master database, you must also move the Resource database to the same location.
But this caused problem during service pack upgrade when users started moving it along with master database. The issue came while applying SP/CU which eventually failed because resource database was moved.
For SQL Server 2008 and above.
This was then fixed by MS and they changed the whole thing such that "user is not allowed to change resource database location" and this is why it was moved to
<drive>:\Program Files\Microsoft SQL Server\MSSQL<version>.<instance_name>\MSSQL\Binnfolder along with other binaries, people normally do not touch contents of BINN folder. It's specifically in BINN folder because it does not contains any USER data only information related to SQL Server.
Yes there was some discrepancy in BOL documents which was later fixed. I wrote an article on this please read Should We Move Resource Database
Moral: Do not move resource database
According to the docs
changing the location of the resource database is not supported or recommended.
It would also appear that a static path is produced for the location of the resource database in the form of
<drive>:\Program Files\Microsoft SQL Server\MSSQL<version>.<instance_name>\MSSQL\Binn\
It would appear there is neither a supported path to change the locations of the resource database files, nor is it recommended to do so.