The limiting directives are 'recommended', because although they are not required for services to operate, many of the limits have default values that might or might not be suitable to your use of services. It is a good idea to set these values yourself rather than relying on what was good for some other user to be good for you.
Limits (CL, NL, OL, BL, LL lines):
These configuration lines are used to set limits on user data within services.
CL Maximum number of registered channels (Default: 10)
NL Maximum number registered nicknames (Default: 5) [not enforced]
OL Maximum number channel operator access entries per channel (Default: 25)
BL Maximum number akick list entries per channel (Default: 30)
LL Maximum number nickserv access entries per nickname
(Default: 3) OL:251 BL:100 LL:10 CL:10 NL:5