Product Lead Growth is it a necessity?

I agree, most companies are shifting towards a PLG model. Even in the B2B space, it’s required as the world becomes more accustomed to specific user experiences and user-driven feedback loops. PLG is essentially the product version of “If you build it, they will come.” 

Is it always necessary? No, there are exceptions. When you’ve built your product on top of another platform, you just have to remain true to that platform’s branding and design (they do the “heavy work” while you’re just ensuring the user has a consistent experience on your product). Another scenario is when you’re in a Red Ocean Market - you’ll find that you need to be “people and product first” to really get an upper hand over your competitors. Otherwise, you’ll end up in a space where you’re simply chasing after your competitors and never innovating (the PM team effectively becomes a “feature team” with most of the requirements aligning to what competitors have). 

Either way, PLG is a large investment and a pivot (and a half) for some organizations. Older and large products have the “if it isn’t broke, don’t fix it” mindset. They’re still profitable and they’re still doing well, just that they keep themselves in the same habit and behaviors they’ve always had.