If you invest in the stock market and tilt your investments slightly away from the norm to achieve a higher long term growth, all that time the market was choppy and you kept accumulating say 10 - 15 years and then things really take off you will see outstanding growth.
But if you spend say 5 - 10 years in cash interest accounts instead, you’ll miss those accumulation years and when things take off, cash will be absolutely obliterated.
Help to save probably gets beat over a 4 year period by placing £50 per month into the stock market. And even if it does not now, it will over a longer period.