As you said, balancing issues.

Imo they can readd it just fine u get tons of cobble in few seconds with just an explosion pickaxe, but it would damage the underground of the terrain, generating cobblestone would fix that even if it is slower than explosion, at least it is a bit of passive cobblestone income with the price of some fuel (KeeWee add something like this to your suggestion, say why it would be better for the server lol)

you see, cobble ==> gravel
may i say more

Did... did no one bother to read the last bit? ("Higher time and energy cost")

Also, if the cobblestone option seems too cheesy/OP, then we should get the ability to grind Stone into Cobblestone. That seems more balanced considering the labor/energy required to operate the machines depending on the machine you use

Yes. It's pointless that you can't grind Stone into Cobblestone in Grind Stone as it's stated literally in it's name.
The possible forms I can see of re-introducing a way to obtain cobblestone through SF are:
-> Grind Stone : Stone to Cobblestone
-> Ignious Processor : Cobblestone with the same previous status or an increased status (followed up by an similar increase to the remaining Ignious Processor's outcome items)
-> High Pressured Chamber : Any basic SF dust/ingot (excludes radioactive ingots) to Cobblestone (through) re-fusion
-> Cobblestone Maker (New "manual" machine - a primitive version on Ignitious Processor) which uses lava buckets as fuel to form Cobblestone (ratio of 1:16 with a 2 minutes "lifespam")

"keewee" please dont doubt our ability to read.
please understand that energy is not an issue to someone who has 240kJ in storage

and cobble is so commonly found that its addition would be "useless" and may cause more issues that benefits.
(as all of it's [better] blocks are already possible with stone in the IP)

Exactly what issues would re adding it to the processor cause?

Massive production of silver and death of current economy

you could generate gravel instantly for like two months
the economy didnt die then

Human, you can still "easily" mass produce silver if you wish so that's not valid.

Frog the economy didn't died because silver price was so nerfed that was worthless.

Sasuke I know you can already mass produce gravel (raw silver) but adding another way to do so will help the death of current economy.

humanerror, silver wasn't nerfed until around a month into having the processor produce cobble and the economy still didn't collapse

"the economy didn't collapsed" you think current eco is in a good shape?

yes inflation isnt bad

Human to be precise the current "economy" revolves in 3 aspects. Crafts. Raw Energy (Coal, Melon, etc...) and Raw Valuable Resources (Gold, Diamond, Netherite and Coal).

At the current matter of speaking, they all are somewhat self renewable. Crafts can be easily mass produced. Melon Farms and Charcoal to Coal Farms take care of energy. Diamonds and Gold are mainly obtained from a non renewable resource (mining) but are helped by one that indeed is (voting). Netherite is through Boss Fighting.

Beside, the main reason for both cobblestone/gravel removal and silver value drop was due to players being able to produce 10k in a matter of few hours due to silver drop rate. However, as the silver rate was fixed, or so it was said, the value returned to it's original value.

While indeed re-adding cobblestone to the equation can threat the unstable economy, the economy is already remnant, being the condition to it's reintroduction that it requires more steps and more work for the same result.