Fleet boosts (links) are a challenging topic. As they stand right now, they're heavily broken because there's virtually no way a pilot can know if another ship is being linked before deciding to take a fight, nor is there any record of that fleet booster's participation in the fight. It's a largely silent mechanic.
Instead, a single ship sits alone in the depths of space, completely isolated from its fleet, providing a system-wide boost to all ships beneath it in the fleet structure. That fleet booster will never see either its fleet members or the enemy ships. Pretty much the only meaningful gameplay that ship needs to do is watch short scan for probes and incoming ships, and remaining aligned to quickly warp out to escape anyone trying to take it out. Its function is very similar to sitting at a safe and hoping you don't get probed down. For all intents and purposes, it's not playing the same game as anyone else in system. When attacking, by default you'll need a probing character with Virtue implants to be able to get a 100% lock on a halfway decent boosting fit.
And yet, links are viewed as absolutely essential to any well-run fleet. Even some individual and small-gang pilots (I use individual to refer to multiboxing individual pilots running multiple ships; they are not solo) will absolutely require links before undocking.
The demands of large fleets and small gangs are very different, and whether fleet boosts are present or absent affects each differently. In most large fleets, links help increase survivability, but not necessarily viability; they keep ships alive, but the fleet would operate similarly with or without links. In other cases - such as doctrines that rely on additional webbing range or glass cannon sniper fleets (Tornadoes, slippery pete Tengus) that need additional lock range - links are absolutely vital to effectively fly the doctrine. A slippery pete doctrine that operates within a Maelstrom fleet's lock range stands no chance, for instance.
For small gang work, links can often mean the difference between using and not using a given ship. many kiting ships, for instance, rely on a speed advantage - often coupled with implants - to maintain range, and without it, they simply wouldn't have a role. Links also provide a meaningful advantage when facing the blob; without links, the solo pilot doesn't stand a chance, so no fight happens.
It's a thorny problem. And CCP has decided to tackle it