Given the size and budget of many clients, most of the work at the SA level involves troubleshooting/implementing solutions in the realm of desktop support and basic server and networking challenges. Even without regard to one's position, client environments are usually small and only a handful go beyond a handful of servers and a firewall. Opportunities to work on and really dig deep into more advanced networking, storage, and server architecture. This may vary between the clientele handled by each team but it is nonetheless frustrating.
Chances to work with virtualization beyond handfuls of ESXi hosts (other platforms are nearly nonexistent) since anything bigger is almost always going to be hosted and handled by someone else. While it can be good to standardize on certain brands and implementations because they're tried and true solutions that most staff are experienced with, alternate vendors, platforms, and other approaches that may better suit the client but don't fit our standard recipes are rarely considered on merit. There's also often a push to replace to replace or at least an unreasonable bias against anything in client environments that doesn't fall under our usual territory. This only serves to prevent broadening the collective expertise to more platforms and is not, in my opinion, in line with the culture of the company.
The emphasis and reliance on cloud services significantly reduces the available complex and interesting work and, by extension, opportunities to grow and learn new platforms (this applies to the above points as well). It can be discouraging to see technologies "roped off" and beyond the realm of anything one might work with. Make no mistake - it's often the sensible choice for the client and in their best interest in terms of budget and what they actually need. Other times it can really seem pushed or forced just to make a sale and generate revenue without doing any work. This can also be particularly frustrating when one of these services has problems that we cannot touch and it often feels as if we're a middleman.