While it's of course true that the most wealthy find numerous ways to avoid IHT, including offshoring assets, it's nevertheless an inconvenient fact that the bulk of intergenerational wealth transfers are 'middle class' ones. That's due to the inexorable increase in house values over the past 50 years, and the fact that when an average UK house (now worth about £350k) is inherited it will only usually result in a very small IHT bill relative to its accumulated capital appreciation.
That is illustrated by the fact that annual IHT receipts are less than 1/1000th (ie 0.1%) of the total value of UK housing stock, which has been growing at an average of 9% per year. Once you own property, you will very likely end up passing on the substantial part of the (un-earned) capital gain during your ownership to your heirs (usually your offspring, whether deserving or undeserving).
The people who end up at the bottom of the pile are those who can never afford to acquire property in the first place.