I agree with you that putting money in a bank, especially at 1pct, is a very bad deal, guaranteed to lose real value over time because it is less than inflation. Even a person who is going to take out their ISA in 1-2 years and hence should probably avoid stocks should be able to achieve closer to 5pct per year with an ISA, certainly at least 4pct.
I, however, do bristle when anyone talks about the high returns of the past decade without also mentioning that for the market as a whole, these have been achieved, in part, due to expansion of the P/E multiple. which cannot continue indefinitely. People making decisions today should not compare bank interest rates against 15% when making their investment decisions, and they should consider also the possibility that stocks may go down in value, and should be avoided if the money might need to get withdrawn within less than about 5 years.
Regarding your own historical returns and the risk taken, I note that the MSCI World index, a broad basket of global stocks, returned only about 10% per year in GBP (8% in USD) even over this most excellent (for investors) recent decade. The most common way to achieve 15%+ will have been to own something racier like the NASDAQ index, which has returned nearly 15% in USD and closer to 17% in GBP over the past 10-year period. Although the companies in it are strong, major global companies, which might make it seem low risk, the fact is that today, that index is 2/3 technology and more than 40% of it is the seven US tech giants (Apple, Microsoft, Nvidia, Amazon, Meta (aka Facebook), Broadcom, Google). Those stocks tend to move with a degree of correlation and they are all highly valued. Those companies are still 20% of MSCI World so well represented there, but less predominant.
Maybe you were clever or lucky enough to beat the MSCI World Index by 5 points and earn 15% without investing heavily into US technology stocks, but most people are not.