Inactivity leak is an emergency measure to restore liveness when the network stops finalizing blocks. It happens when >33% of validators are offline(WW3 scenario), major bug in widespread implementation, etc.
Your link explains that.
ETH2 is friendly to home stackers - you may lose some profit by being offline sometimes, and in the worst case minor penalties are applied.
EDIT: If you are interested in a much better description of what happens if you are offline, see this:
https://eth2book.info/altair/part2/incentives/penalties
Some points from the link:
- penalties =/= slashing
- If you are online > 42.5% of the sime - you are earning profits
In that case, without any stakes, half of nodes will be locked to NIL, half - to a valid block.
In case of stakes, byzantine proposer (it is only one node that is really byzantine, but it can control how network is split) can partition network according to a proportion of stakes, so that neither half gets prevalence.
The algorithm in the link you provided does nothing in that case. The only node that will be punished is a byzantine validator which does not care.
The system will be in no-progress-possible state indefinitely.
[1]: https://eth2book.info/altair/part2/incentives/inactivity