11k gain per year on a regular basis is either extraordinarily lucky or based on a very large amount of capital. Yes, over time the annual isa allowance builds up but like I said there was actually no real advantage in early years especially when providers generally imposed fees which exceeded any tax savings. Back in the day PEPs were only something like 5k per year weren’t they?
Even now you’d need about 70k invested to reach the (newly reduced) 2k dividend exemption, and the actual tax payable on say 150k is only a pittance (3% yield = 4500, 2000 exemption and 10% on the rest is 250 quid isn’t it?). Fact is, it’s not hard to avoid paying significant tax on investments of this sort of size, and it would take decades to shelter anything much larger.