A "technicality" in this legal context is a colloquial term that means the spirit of the law losing out to strict adherence to the letter of the law.No need for expensive lawyers when the state breaks your constitutional rights. The 5th amendment is not a technicality.
Cosby freely admitted under oath dosing women up with drugs, and sleeping with the victim Costand on the night she alleged the assault. It's just that the circumstances in which he did so were successfully argued on appeal to be inadmissable for the criminal court case he was convicted in. This means that damning evidence was rejected for a procedural reason rather than its lack of veracity. This is most certainly a "technicality" as anyone usefully understands the term.
And yes expensive lawyers do matter, because 99% of poor people in the same position would still be sitting in the slammer because fair chance their lawyer would at least one of a) not care enough to bother, b) not be competent enough to realise the technicality, c) persuade them to some sort of guilty plea deal that barred the option of appeal.