Star Delta starters are far from obsolete. For example YD starter for 250kW price is about few hundred bucks, soft starter
is around five thousand bucks, and VFD
is around 30k$. Both SS and VFD require additional cost in protection switchgear. If you need constant speed YD is far cheapest solution, even in longer term. On other side if you need or your process allows you to change speed, then VFD is far best solution, also considering economy.