This is very, very true. My personal opinion is that given the complex nature of this particular subject that some are inclined essentially to delegate their conscience to the guidance of the F&DS. So if the F&DS state that product A or procedure B is not acceptable but leave product X and procedure Y to conscience then that's where the individual's conscience will be.
Of course, the whole point of being sheep in the congregation is to look to the leadership of the F&DS as Jehovah's representatives on the earth so in that sense there is nothing inherently wrong in the above however as you state, really we should be reasoning on the matter ourselves to reach a conclusion that keeps our conscience clear and relationship with Jehovah intact.
This is also why the F&DS have pointed out that were our conscience to determine that fractions were unacceptable since blood has had to be donated and processed (noting that we are not permitted to donate blood out of respect for Jehovah's standards) then this would also mean we would need to look carefully at all sorts of products and procedures, including things like some basic vaccinations, that might contain products obtained by processing blood.
As a side point, this also makes me recall conversations I had years ago when a number of congregations in the UK, including one local to me, donated funds to allow local hospitals to purchase cell saver machines. This was welcomed by many however my personal opinion was that this was indicating that the congregation, and by extension, the organisation, supported and endorsed the procedure. This, in turn, could make someone whose conscience did not permit them to submit to the procedure feel out of step with the organisation or feel that their position was somehow incorrect even though the literature made it clear this was a conscience matter. It could also cause a problem for an individual if they were admitted to hospital and declined the procedure since the medical staff would be unable to understand how Jehovah's Witnesses could donate a machine to enable bloodless care to be undertaken yet a Witness, perhaps from the congregation who donated the machine, refused the procedure feeling that they would be not following the biblical command to abstain from blood.