I'll never understand why people say this. If the pension is taken as a lump sum, then it is an asset, and is a component of net worth.
Until then, it is only a potential future income stream. If the holder dies, there is no value at all.
That is generally true for traditional defined benefit pensions, although even in that case, some would argue that any guaranteed right to receive future cash inflows meets the definition of an asset, especially if there are survivor benefits. And some consider it a bond-equivalent for AA purposes. I think there are reasonable arguments either way on those points. But FWIW, there is some rather obscure AICPA guidance for personal financial statements, which specifically excludes life-contingent pensions from net worth.
However OP appears to have a DC cash balance pension. DW had such a pension when working. She was required to contribute X% of her salary each paycheck and the balance grew according to the performance of the underlying pension trust assets. She was 100% vested in the balance, so if she had left that employer, she would have taken her balance and rolled it into an IRA. There was also an option to leave it at the employer and receive an annuity at some future date, like age 65, which sort-of sounds like what OP is describing. Turns out, DW retired from this employer and now receives the monthly annuity.
So... prior to her retirement, I included the pension cash balance as an asset in net worth, since we had the right to receive that money at any time had she terminated employment. It was essentially no different than a 401K balance at that point, except we did not control the underlying investments. After retirement, I do not include it because it is now just a guaranteed monthly cash inflow, which will stop when she dies (single life annuity option).
We definitely count the estimated market value of our rental property in net worth. The net cash flow it generates is just another income source, which reduces our need for portfolio withdrawals.
