Good Wi-Fi reaches everywhere you need it to, and works the first time, every time, without cutting in and out.
Once you exceed a certain square footage -- or exceed a certain number of simultaneous users, a single Wi-Fi router or access point no longer cuts it.
Neighbors can also present a challenge, especially if you are in a high rise building.
A well placed access point may adequately cover 2000 square feet in an open plan, single story, detached building in the suburbs. Locations in office towers and in dense business districts present the challenge of interference from above, below, and to all sides. In these settings, a single access point may only successfully cover 300 square feet or so. Neighbors with new high-powered wireless access points, may drown out the Wi-Fi solution that used to work great just a few years ago.
Commercial systems (like Meraki, Ubiquiti, Aruba) can be differentiated by a "controller".
Home and small business routers are mostly meant to work independently. A basic solution can be to simply purchase multiples of inexpensive wireless routers, and set the same network name and password on each. A "controller" based system is a step up from this. It can provide more consistent service as it keeps track of the real-time connection quality each wireless device and can coordinate seamless hand offs between access points. Move your laptop from one side of the office, or even one floor to another, without your Zoom calls skipping a beat!
Mesh systems can provide a substantial improvement at a relatively low cost, but are a compromise solution.
Systems such as Nest Wifi, Eero, Linksys Velop, Netgear Orbi, and others can provide nearly instant coverage to a space by establishing a wireless mesh between multiple units. This provides a great improvement quickly and at a relatively low cost if you have problems with wireless dead zones, but it is at heart a compromise solution. Videoconference steams can be delayed and can dropped as they are handed wirelessly between multiple mesh points, before reaching the wired "trunk" to the internet at large. Wired networks are generally immune to interference and can easily handle more simultaneous traffic with less latency. The industry standard in corporate networks is to have all access points backed by wire, so there is only one wireless "hop" from your device to the wired trunk network. Setting up a network the tried-and-tested way with wire to where it is needed, as opposed to wireless-on-top-of-wireless may cost less than you may expect.