I work in a data center with throughput speeds up to 2GB over fibre and we use tie wraps on our Cat5 and fibre all the time. We just use a little finesse and don't cinch them down. Recently we have moved to Velcro® cinchers because we're constantly moving cabling.

We've must have on the order of miles of cabling in rack cabinets, overhead, and beneath our raised floor and most of it is laced to cable trays or guides of some sort.

Even in straight runs fibre can become damaged by excessive external pressure, but applied correctly nylon cable ties are the defacto industry standard.