The suggestion of £300 payment by its very nature of only applying to mortgage holders is de facto prioritising them.
It is also unlike the help that a few renters on very low incomes with next to no savings already get. That’s more comparable to the help that a few mortgage holders on very low income with next to no savings get- as in housing benefit applied to the interest charges as an interest free loan.
If this were implemented it is actually presumably unlikely renters who get no help no would get any help at all. During the Covid mortgage holidays for anyone who asked regardless of circumstance, was there any similar help for renters? No, there was not. There was no rent holiday. Only empty exhortations for landlords to #bekind and a moratorium on evictions.
Renters would not benefit from a £300/mo handout to mortgage holders because it’s highly doubtful that this would be paid to landlords per property they lease out. And even if it were, there would be no legal requirement to pass on this savings to the renter by reducing their rent. Most landlords would pocket the £300/mo per property and leave the rent where it is. At most, they might decide to not increase the rent that year….but it’s within their sole discretion.
As we saw with the Covid mortgage holidays, while landlords took advantage of them, there was no passing down and giving their tenants a rent holiday. At most they pretended a kindness of oh, if you can’t pay rent I’ll be nice about giving you to to pay back the rent arrears (when they couldn’t evict anyway…).