Question on alignment

In copydir.c:copy_file() I read

    /* Use palloc to ensure we get a maxaligned buffer */
    buffer = palloc(COPY_BUF_SIZE);

No data type wider than a single byte is used to access the data in the
buffer, and neither read() nor write() should require any specific alignment.
Can someone please explain why alignment matters here?

-- 
Antonin Houska
Web: https://www.cybertec-postgresql.com