I think I know where OP is coming from.
When you have superannuation, you don’t personally have a capital gains event when the fund (whether a managed fund or an SMSF) sells what it owns - but the fund does. Once you reach preservation age, and convert your superannuation to retirement phase, there are no capital gains due from a capital gains event, while in accumulation phase, your superannuation capital gain is taxed at 15% if the fund owned the investment for less than a year, or 10% otherwise.
Thus, if you move from one fund to another while you’re in accumulation mode, your super would have a capital gains event, and be taxed appropriately. However, like SMSFs, small APRA funds own individual assets - but each small APRA fund can hold only some of the assets that an SMSF can hold. Depending on whether the assets in the SMSF can be transferred, conversion from an SMSF to one of these funds wouldn’t generate a capital gains event, since the investment hasn’t been sold - just transferred (in specie transfer). As far as I know, later on you could transfer any investments back into your SMSF without generating a capital gains event.
You can also do an in specie transfer of investments from outside super into a small APRA fund or an SMSF.