Landlords can put amost almost condition they like in tenancy agreements and the schedule of rules annexed to those. The use of the fashionable phrase 'health and safety' is annoying, but such conditions as this have been put mechanically in agreements by landlords for many decades, long before the phrase was common . A condition that 'common parts' 'hallways' etc be kept clear at all times or that no tenant put anything there, is perfectly standard.
The reason for such a condition in agreements may be that the landlords want to minimize the risk of being sued under Occupier Liability laws. Somebody falling over a bookcase or other property left in the common parts could have a claim. The landlord's insurers wouldn't like that, any more than the landlord would. But usually the reason seems to be no more than keeping certain standards up in a block, and preventing any tenant from abusing the practice to the disadvantage of others, by forbidding it altogether.