The policy is aimed precisely at the type of person who doesn't understand the law and thinks landlords evict on a complete whim with zero notice.
The old Section 21 gave a reasonable backstop (usually 2 months' notice after the initial period) so that both sides had an exit route.
Under the new Act, tenants can still give two months' notice and leave whenever they like. Landlords, however, now have to prove a specific ground under Section 8 and go through the courts – which are already notoriously slow (median wait around 6 months or more in many areas).
That means:
A landlord who needs to sell (maybe for retirement, inheritance tax, or their own family circumstances) or move a relative in could be stuck for a very long time.
Bad tenants (rent arrears, damage, anti-social behaviour) become much harder and more expensive to remove. Several experienced ex-landlords on this thread have described exactly that nightmare.
The "sacrifice" you're describing falls entirely on the landlord's side, while the tenant keeps an easy exit.
Private renting only works if enough people are willing to be landlords. When the risk and hassle go up sharply, many (especially small and accidental ones) sell up or sit on the property empty. We're already seeing rents rising and supply tightening in many areas as a direct result.
Homes matter to landlords too – it's often their pension, inheritance, or life savings tied up in bricks and mortar. Treating every landlord as a greedy profiteer who deserves extra punishment ignores the thousands of ordinary people providing housing the state can't or won't supply.
The point of the law was better tenant security. The likely outcome is fewer homes available to rent at all, which makes everyone (especially families with kids in school) worse off. Economics isn't optional here.