It just creates confusion, errors, and bugs.

For one thing, this can cause dup sysfs or procfs nodes to get
created:

[    1.198015] proc_dir_entry '00.0' already registered
[    1.198036] Call Trace:
[    1.198052]  [00000000004f2534] create_proc_entry+0x7c/0x98
[    1.198092]  [00000000005719e4] pci_proc_attach_device+0xa4/0xd4
[    1.198126]  [00000000007d991c] pci_proc_init+0x64/0x88
[    1.198158]  [00000000007c62a4] kernel_init+0x190/0x330
[    1.198183]  [0000000000426cf8] kernel_thread+0x38/0x48
[    1.198210]  [00000000006a0d90] rest_init+0x18/0x5c
Signed-off-by: David S. Miller <davem@davemloft.net>