Only if you use bad equipment and/or don’t evaluate the radio environment. RF in general I would agree, but Wifi is really not that complicated anymore.
Ubiquiti is fine up to a couple of hundred users. We manage around 250 sites (thousands of users and guests) on a single Unifi controller, though management does get a bit slow when provisioning. One UAP-AC-Pro covers about 1000 sqft in a typical scenario (25-30 users), but can reliably service a larger area with 40-50 users without any calls to service desk.
Cisco Meraki is very nice for office spaces and provide great throughput for more demanding scenarios.
Huawei and Ericsson have alot of great wireless repeaters, if you have ISP contacts or a really nice supplier.