The largest barrier to accelerated life testing right now is that we really don't know all the mechanisms that cause degradation (or understand their impact on stability). There are many lab instruments that already provide HALT metrics on how stable a drug sample is expected to be under different conditions. And the Arrhenius and Eyring equations are useful for empirical modeling. These tools are great for quickly identifying when formulations are unstable. But it's very difficult to say with certainty (at least in the pharma world) that something will be stable for X years unless you actually test it for X years.
For the vast majority of manufactured products, HALT makes sense because any uncertainty that remains after testing is not likely to harm users. But with some of these drugs, any uncertainty, even after HALT, could cause major problems for users. And it seems that the FDA is unwilling to accept that risk. But as far as I know, the FDA is actively seeking methods for performing HALT that produce accurate and repeatable results.
For the vast majority of manufactured products, HALT makes sense because any uncertainty that remains after testing is not likely to harm users. But with some of these drugs, any uncertainty, even after HALT, could cause major problems for users. And it seems that the FDA is unwilling to accept that risk. But as far as I know, the FDA is actively seeking methods for performing HALT that produce accurate and repeatable results.