The thing about comparing Hallownest and Pharloom is that the former is ridiculously young.
Hallownest is better than Pharloom because it didn't have the time or advantages to be as bad as pharloom before the radiance hit the nuke button
If I remember correctly, the weaver settlement of deepest predates the pale king's arrival, or at least the foundation of hallownest proper.
By the time these weavers fled Grand Mother Silk, pharloom was likely an established kingdom (or at least a group of territories) comparable with hallownest at its peak, with weaver structures littered all across the territory and a number of already old societies in the Order of Karak, Verdania, the Skarr and likely others.
Pharloom's ailing state with the creation of the citadel to feed and contain GMS begins, at the absolute earliest and being generous, a generation or two before hallownest birth, when the weavers that manage to scale settle in deepnest.
It took likely a millennium equivalent or two for hallownest of founding, recruitment, building, expanding, infection 1.0, devising a plan, creating and training the perfect vessel, sealing the radiance, rebuilding and resuming as usual, the vessel failing, infection 2.0, full fall of the kingdom and the infected stasis before the knight arrives and finally pulls the plug.
In that whole life cycle of hallownest (plus however long took between the end of the infection and hornet getting captured, maybe a week maybe a century), those devoted to GMS had the time to create the citadel (if it wasn't already there at least in part) to substitute the weavers keeping the silk and song churning along, with the explicit advantage of plentiful metal in the bell veins and the abundant heat of the running magma bellow to grow to require the evils we see first hand.
Putting the nuke that the radiance was out of the equation, how long do you thing it would take for something similar to occur to hallownest as it happened to pharloom.
How long before PK's slow but steady expansion crosses the line with the mantises or the bees like it started to do with the spiders right before the debacle?
How long before he becomes an even farther figurehead, turning a blind eye as the mortal high caste or the sanctum scholars assume more power than they already had and turn the city of tears into another citadel that chokes the life around it?
Or before the injustices of those outcast and disillusioned bugs like xero pile enough to chip away at his benevolent facade and pale bright promises and decides to tighten his grim like GMS did with the weavers?
Maybe his hubris in tinkering with intrinsically uncontrollable forces unleashes a calamity the likes of which makes the infection look quaint
Honestly, with the lengths we've seen the Pale Monarchs of hallownest go on the off chance that it might save the kingdom and the evil and injustices we've seen only in the shadow of moribund bugs, given enough time and the PK's direct involvement, hallownest might have grown to be an even worse place than pharloom ever could.