Huh? HSBC/First Direct would have been losing money on the Regular Saver accounts. Why do you think no one else was offering such high rates?
Still, if your want to blame someone for this reduction in the savings rate, you should probably have a go at the regulators.
The fact the HSBC had to set up a separate ringfenced operation in the UK means they now have lots of excess deposits here and don’t need any more (previously they could have used that money globally)
Especially since HSBC are one of the few banks who lend out less than they take in deposits.