I have spent most of my working life outside GB, with a couple of short returns (never again). I've worked in the Far East, Australasia, very short stint in USA, bit longer in Middle East and now happily in central/Southern Europe (depending upon how you look at it). I speak or spoke the language in all except the Middle East.
The fact is, in most countries, to get to know established locals properly, on a personal basis is difficult. They've got their lives, friends, families established. They take for granted what to you is new and unknown, to the extent that it never occurs to them that you can not or do not know. Fellow foreigners who have overcome the initial hurdles, found out how and where to find accommodation at the normal price and where to shop for the sorts of things that expats. need but locals grew up with; what tax advisers, lawyers, banks understand and can, for a reasonable charge, help one to manage assets or liabilities, or writing a will and so on for two different legal and tax regimes, registering with local authorities (even if it is necessary or not) and so on; these people are invaluable. Things like getting medical help at 2 in the morning - where is the hospital? Should I call the GP? Have I got a GP who speaks enough English or whatever language I know? Just had a minor accident in the car - do I have to report it? (In some places, no one will do repairs without a police report).
Having young children helps, if they are at the local schools. Otherwise, one can live for years without making close friendships with a local, not through anyone's fault.
Going into the average bank for advice about how to transfer foreign creditworthiness may work in the centre of Zurich or Brussels. In most banks, the staff will hardly be better informed than you.
It's all very well to be snooty about other expats., no doubt they are at least as snooty about you. But if in a new land, where the language (including American) is not yours, where customs and laws differ from yours, all help should be seized with gratitude. Americans are classic examples: they seem to speak almost the same language - except it has, apart from grammatical and vocabulary differences - different idioms, references, background and semantics - full of false friends (linguistically). Their culture is to be overwhelmingly smiley, "you're my soulmate", "you must come to dinner/come for picnic/borrow my spare car"..... Sadly, see them a couple of days later they've probably almost forgotten who you are - not rudeness, just the culture - easy in - easy out.
No, if you want to know how to insure your 15 year old sports car (in a place where insurers will not touch a car over 10 years old) or a tax adviser who speaks some of your language and can handle your assets spread across two or three countries or a bank that will handle regular transfers abroad at a lower charge than the amount being transferred, or how to get tickets to that event or which beaches to avoid - fellow foreigners are your friends. If you need to find a kindergarten that will have patience with your child who has not yet learnt the local language (I know of children who, in reaction to unsympathetic handling, started to actively refuse to speak the local language), you need someone who understands the problem and has overcome it.
Over time, you should become localised, though you will always be a foreigner; if you marry a local, it may happen a bit quicker, a bit more thoroughly, your language skills should become much better. But you will always be a foreigner and even if you no longer need help, at least until the funeral arrangements come, you can help others.
I have come across expatriates who never learn the language. In Asian countries this can be very, very difficult and the disparities between the foreigner¨s way of life and that of even a prosperous local are radically different. Even in Europe, if you work for a large, international firm, if the working language is English and your spouse is English speaking and you work long hours, you will find it very hard to learn much more than how to ask for a glass of beer, even if you take lessons. Francophone areas should be easier, as most Britons, for example, do some French at school and, in my experience, it is rare to meet a foreigner in Geneva who can not cope fairly well and often much better than that, in French. German seems to be less common. Arabic, Chinese languages - rare (I can speak a Chinese language; but my job required it).