That’s definitely true, but everything comes with a price
For the SP part: SP pots are not expensive at all, compared with tens of millions of silver you may otherwise have to invest into attributes.
For the taking damage part: this can be countered with a proper build. Let’s say Cryo3 Soc 2 and Thaum 2(as R8), full Con. You can transpose into high INT to summon, and ride your summon as a full Con char (yes full INT build will have higher stats but will be much more tedious if you don’t have your personal healer). With Thaum 2 right arm buff + shield (the new 11 Con 96 MDEF 117 DEF shield from 190 dungeon is a good one), Cyro 125% MDEF from shield attribute, sub-zero shield (still works with everything in PVE last I checked) and ice tree, most mobs will not be able to do much damage to you even if you stand still (not for ET obviously), plus ice tree will get the mobs together for your AOE.