There is some documentation of the repeated collateral damage to one user (which
this would fix) at [[w:en:User:WBardwin/AOL_Block_Collection]].

Suggest WONTFIX (especially enforcement of such a limit). There are certainly cases when indef-blocking an IP address is legitimate. Many wikis might adopt a more hardline approach to indef-blocking, and throwing an error/warning message on every attempt at indef-blocking seems to be more annoying than helpful.

I would suggest that enwiki A) Customize their block page info to include a note about indef-blocking IPs--if they don't, I haven't read it in awhile, and/or B) Perhaps put in some site JS to enforce/encourage such a limit.

I don't understand Chad's reasoning. If a wiki doesn't want to use this feature, then it wouldn't have to. Although I didn't write the original request, I don't read it as hard-coding the IP ranges into the software; instead, the administrators of the wiki would add IP ranges to a wiki-specific list with suggested upper limits for block times. Those wikis that wish to allow indefinite blocking of all IPs without warning could still do so. And of course, even the English Wikipedia would allow indefinite blocking of most IPs, even if this were to be fully implemented there.

It is true that [[Special:Block]] at that wiki no longer has text about 15-minute limits; I'm not sure that any of those apply anymore. Instead, there is some even more serious text about alerting the Wikimedia Foundation when blocking government IPs! A feature that allowed wikis to include warning messages when blocking certain IPs for certain lengths of time would be very useful for that as well (as it could throw up the warning for blocking these IPs for any length of time whatsoever).

I missed the part about using a list of IPs, I read it as "enforce some arbitrary upper limit on all IP blocks." I didn't have my caffeine this morning :-\

Still not terribly convinced of the usefulness, however.