I’d argue against this. I did a sample calculation where the outcome was that the tax advantage you mention is “only 0.2%”. Sure it’s just one case and YMMV, it depends on concrete numbers so maybe my calculation is too simplistic…
But let’s assume 0.2% tax advantage is realistic, that must be compared with 3a investment cost, which is easily 0.3% more expensive than outside 3a (viac vs IB is probably 0.4% more expensive).
So I think it’s really relative… imv the big advantage of 3a is the initial income tax saving (and the saving effect it has on people)